phosphoacceptor receiver (REC) domain of response regulators (RRs) and pseudo response regulators (PRRs); Two-component systems (TCSs) involving a sensor and a response regulator are used by bacteria to adapt to changing environments. Processes regulated by two-component systems in bacteria include sporulation, pathogenicity, virulence, chemotaxis, and membrane transport. Response regulators (RRs) share the common phosphoacceptor REC domain and different effector/output domains such as DNA, RNA, ligand-binding, protein-binding, or enzymatic domains. Response regulators regulate transcription, post-transcription or post-translation, or have functions such as methylesterases, adenylate or diguanylate cyclase, c-di-GMP-specific phosphodiesterases, histidine kinases, serine/threonine protein kinases, and protein phosphatases, depending on their output domains. The function of some output domains are still unknown. TCSs are found in all three domains of life - bacteria, archaea, and eukaryotes, however, the presence and abundance of particular RRs vary between the lineages. Archaea encode very few RRs with DNA-binding output domains; most are stand-alone REC domains. Among eukaryotes, TCSs are found primarily in protozoa, fungi, algae, and green plants. REC domains function as phosphorylation-mediated switches within RRs, but some also transfer phosphoryl groups in multistep phosphorelays.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1501583231  14 ILVAEDDSILRPLLVELLDEMQFEVIAAEDGTKAMALLQdldcNHMHVDLLLTDIGLPG-VNGNKLAEFARKIWPNLSIL 92
Cdd:cd18161     1 VLVVEDDPDVRRLTAEVLEDLGYTVLEAASGDEALDLLE----SGPDIDLLVTDVIMPGgMNGSQLAEEARRRRPDLKVL 76

                          90       100
                  ....*....|....*....|....*.
gi 1501583231  93 FITGYAH-GINTMTLDNKIQLLTKPF 117
Cdd:cd18161    77 LTSGYAEnAIEGGDLAPGVDVLSKPF 102

phosphoacceptor receiver (REC) domain of hybrid sensor histidine kinase/response regulators similar to Pseudomonas savastanoi blue-light-activated histidine kinase; Typically, two-component regulatory systems (TCSs) consist of a sensor (histidine kinase) that responds to specific input(s) by modifying the output of a cognate response regulator (RR). TCSs allow organisms to sense and respond to changes in environmental conditions. Hybrid sensor histidine kinase (HK)/response regulators contain all the elements of a classical TCS in a single polypeptide chain. Pseudomonas savastanoi blue-light-activated histidine kinase is a photosensitive HK and RR that is involved in increased bacterial virulence upon exposure to light. RRs share the common phosphoacceptor REC domain and different effector/output domains such as DNA, RNA, ligand-binding, protein-binding, or enzymatic domains. REC domains function as phosphorylation-mediated switches within response regulators, but some also transfer phosphoryl groups in multistep phosphorelays.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1501583231  14 ILVAEDDSILRPLLVELLDEMQFEVIAAEDGTKAMALLQdldcNHMHVDLLLTDIGLPG-VNGNKLAEFARKIWPNLSIL 92
Cdd:cd18161     1 VLVVEDDPDVRRLTAEVLEDLGYTVLEAASGDEALDLLE----SGPDIDLLVTDVIMPGgMNGSQLAEEARRRRPDLKVL 76

                          90       100
                  ....*....|....*....|....*.
gi 1501583231  93 FITGYAH-GINTMTLDNKIQLLTKPF 117
Cdd:cd18161    77 LTSGYAEnAIEGGDLAPGVDVLSKPF 102

Response regulator receiver domain; This domain receives the signal from the sensor partner in bacterial two-component systems. It is usually found N-terminal to a DNA binding effector domain.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1501583231  14 ILVAEDDSILRPLLVELLDEMQFEVIAAEDGTKAMALLQdldcnHMHVDLLLTDIGLPGVNGNKLAEFARKIWPNLSILF 93
Cdd:pfam00072   1 VLIVDDDPLIRELLRQLLEKEGYVVAEADDGKEALELLK-----EERPDLILLDINMPGMDGLELLKRIRRRDPTTPVII 75

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|..
gi 1501583231  94 ITGYAhgintmTLDNKIQL--------LTKPFSLGVLTKRIE 127
Cdd:pfam00072  76 LTAHG------DEDDAVEAleagaddfLSKPFDPDELLAAIR 111

cheY-homologous receiver domain; CheY regulates the clockwise rotation of E. coli flagellar motors. This domain contains a phosphoacceptor site that is phosphorylated by histidine kinase homologues.

                           10        20        30        40        50
                   ....*....|....*....|....*....|....*....|....*....|....*...
gi 1501583231   14 ILVAEDDSILRPLLVELLDEMQFEVIAAEDGTKAMALLQDLdcnhmHVDLLLTDIGLP 71
Cdd:smart00448   3 ILVVDDDPLLRELLKALLEKEGYEVDEATDGEEALELLKEE-----KPDLILLDIMMP 55

phosphoacceptor receiver (REC) domain of hybrid sensor histidine kinase/response regulators similar to Pseudomonas savastanoi blue-light-activated histidine kinase; Typically, two-component regulatory systems (TCSs) consist of a sensor (histidine kinase) that responds to specific input(s) by modifying the output of a cognate response regulator (RR). TCSs allow organisms to sense and respond to changes in environmental conditions. Hybrid sensor histidine kinase (HK)/response regulators contain all the elements of a classical TCS in a single polypeptide chain. Pseudomonas savastanoi blue-light-activated histidine kinase is a photosensitive HK and RR that is involved in increased bacterial virulence upon exposure to light. RRs share the common phosphoacceptor REC domain and different effector/output domains such as DNA, RNA, ligand-binding, protein-binding, or enzymatic domains. REC domains function as phosphorylation-mediated switches within response regulators, but some also transfer phosphoryl groups in multistep phosphorelays.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1501583231  14 ILVAEDDSILRPLLVELLDEMQFEVIAAEDGTKAMALLQdldcNHMHVDLLLTDIGLPG-VNGNKLAEFARKIWPNLSIL 92
Cdd:cd18161     1 VLVVEDDPDVRRLTAEVLEDLGYTVLEAASGDEALDLLE----SGPDIDLLVTDVIMPGgMNGSQLAEEARRRRPDLKVL 76

                          90       100
                  ....*....|....*....|....*.
gi 1501583231  93 FITGYAH-GINTMTLDNKIQLLTKPF 117
Cdd:cd18161    77 LTSGYAEnAIEGGDLAPGVDVLSKPF 102

CheY-like REC (receiver) domain, includes chemotaxis protein CheY and sporulation regulator Spo0F [Signal transduction mechanisms];

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1501583231   8 QKTKKIILVAEDDSILRPLLVELLDEMQFEVIAAEDGTKAMALLQDLdcnhmHVDLLLTDIGLPGVNGNKLAEFARKI-- 85
Cdd:COG0784     2 PLGGKRILVVDDNPDNRELLRRLLERLGYEVTTAEDGAEALELLRAG-----PPDLILLDINMPGMDGLELLRRIRALpr 76

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|....*...
gi 1501583231  86 WPNLSILFITGYAH-GINTMTLDNKIQ-LLTKPFSLGVLTKRIEELIS 131
Cdd:COG0784    77 LPDIPIIALTAYADeEDRERALEAGADdYLTKPVDPEELLEALRRLLA 124

Response regulator receiver domain; This domain receives the signal from the sensor partner in bacterial two-component systems. It is usually found N-terminal to a DNA binding effector domain.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1501583231  14 ILVAEDDSILRPLLVELLDEMQFEVIAAEDGTKAMALLQdldcnHMHVDLLLTDIGLPGVNGNKLAEFARKIWPNLSILF 93
Cdd:pfam00072   1 VLIVDDDPLIRELLRQLLEKEGYVVAEADDGKEALELLK-----EERPDLILLDINMPGMDGLELLKRIRRRDPTTPVII 75

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|..
gi 1501583231  94 ITGYAhgintmTLDNKIQL--------LTKPFSLGVLTKRIE 127
Cdd:pfam00072  76 LTAHG------DEDDAVEAleagaddfLSKPFDPDELLAAIR 111

phosphoacceptor receiver (REC) domain of response regulators (RRs) and pseudo response regulators (PRRs); Two-component systems (TCSs) involving a sensor and a response regulator are used by bacteria to adapt to changing environments. Processes regulated by two-component systems in bacteria include sporulation, pathogenicity, virulence, chemotaxis, and membrane transport. Response regulators (RRs) share the common phosphoacceptor REC domain and different effector/output domains such as DNA, RNA, ligand-binding, protein-binding, or enzymatic domains. Response regulators regulate transcription, post-transcription or post-translation, or have functions such as methylesterases, adenylate or diguanylate cyclase, c-di-GMP-specific phosphodiesterases, histidine kinases, serine/threonine protein kinases, and protein phosphatases, depending on their output domains. The function of some output domains are still unknown. TCSs are found in all three domains of life - bacteria, archaea, and eukaryotes, however, the presence and abundance of particular RRs vary between the lineages. Archaea encode very few RRs with DNA-binding output domains; most are stand-alone REC domains. Among eukaryotes, TCSs are found primarily in protozoa, fungi, algae, and green plants. REC domains function as phosphorylation-mediated switches within RRs, but some also transfer phosphoryl groups in multistep phosphorelays.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1501583231  15 LVAEDDSILRPLLVELLDEMQFEVIAAEDGTKAMALLQDLdcnhmHVDLLLTDIGLPGVNGNKLAEFARKIWPNLSILFI 94
Cdd:cd00156     1 LIVDDDPAIRELLKSLLEREGYEVDTAADGEEALELLREE-----RPDLVLLDLMMPGMDGLELLRKLRELPPDIPVIVL 75

                  ....*
gi 1501583231  95 TGYAH 99
Cdd:cd00156    76 TAKAD 80

Two-component response regulator, YesN/AraC family, consists of REC and AraC-type DNA-binding domains [Signal transduction mechanisms, Transcription];

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1501583231  14 ILVAEDDSILRPLLVELLDEMQ-FEVIA-AEDGTKAMALLQDLdcnhmHVDLLLTDIGLPGVNGNKLAEFARKIWPNLSI 91
Cdd:COG4753     2 VLIVDDEPLIREGLKRILEWEAgFEVVGeAENGEEALELLEEH-----KPDLVITDINMPGMDGLELLEAIRELDPDTKI 76

                  ....*..
gi 1501583231  92 LFITGYA 98
Cdd:COG4753    77 IILSGYS 83

phosphoacceptor receiver (REC) domain of Brucella abortus CpdR and CckA, and similar domains; Two-component systems (TCSs), consisting of a sensor and a response regulator, are used by bacteria to adapt to changing environments. Processes regulated by TCSs in bacteria include sporulation, pathogenicity, virulence, chemotaxis and membrane transport. Response regulators share the common phosphoacceptor REC domain and differ output domains such as DNA, RNA, ligand, and protein-binding, or enzymatic domain. CpdR is a stand-alone REC protein. CckA is a sensor histidine kinase containing N-terminal PAS domains and a C-terminal REC domain. CpdR and CckA are components of a regulatory phosphorelay system (composed of CckA, ChpT, CtrA and CpdR) that controls Brucella abortus cell growth, division, and intracellular survival inside mammalian host cells. CckA autophosphorylates in the presence of ATP and transfers a phosphoryl group to the conserved aspartic acid residue on its C-terminal REC domain, which is relayed to the ChpT phosphotransferase. REC domains function as phosphorylation-mediated switches within response regulators, but some also transfer phosphoryl groups in multistep phosphorelays.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1501583231  14 ILVAEDDSILRPLLVELLDEMQFEVIAAEDGTKAMALLQdldcNHMHVDLLLTDIGLPGVNGNKLAEFARKIWPNLSILF 93
Cdd:cd18160     2 ILLADDEPSVRKFIVTTLKKAGYAVTEAESGAEALEKLQ----QGKDIDIVVTDIVMPEMDGIELAREARKIDPDVKILF 77

                          90       100
                  ....*....|....*....|....*.
gi 1501583231  94 ITGYAHGINTMTLD--NKIQLLTKPF 117
Cdd:cd18160    78 ISGGAAAAPELLSDavGDNATLKKPF 103

phosphoacceptor receiver (REC) domain of NarL (Nitrate/Nitrite response regulator L) family response regulators; The NarL family is one of the more abundant families of DNA-binding response regulators (RRs). Members of the NarL family contain a REC domain and a helix-turn-helix (HTH) DNA-binding output domain, with a majority of members containing a LuxR-type HTH domain. They function as transcriptional regulators. REC domains function as phosphorylation-mediated switches within response regulators, but some also transfer phosphoryl groups in multistep phosphorelays.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1501583231  14 ILVAEDDSILRPLLVELLDEMQ-FEVIA-AEDGTKAMALLQDLDCnhmhvDLLLTDIGLPGVNGNKLAEFARKIWPNLSI 91
Cdd:cd17535     1 VLIVDDHPLVREGLRRLLESEPdIEVVGeAADGEEALALLRELRP-----DVVLMDLSMPGMDGIEALRRLRRRYPDLKV 75

                  ....*.
gi 1501583231  92 LFITGY 97
Cdd:cd17535    76 IVLTAH 81

histidine kinase; Provisional

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1501583231  14 ILVAEDdsilRPLLVEL----LDEMQFEVIAAEDGTKAMALLQDldcnHMHVDLLLTDIGLPG-VNGNKLAEFARKIWPN 88
Cdd:PRK13557  418 ILIVDD----RPDVAELarmiLEDFGYRTLVASNGREALEILDS----HPEVDLLFTDLIMPGgMNGVMLAREARRRQPK 489

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|....*...
gi 1501583231  89 LSILFITGYA------HGINTMTLDnkiqLLTKPFSLGVLTKRIEELI 130
Cdd:PRK13557  490 IKVLLTTGYAeasierTDAGGSEFD----ILNKPYRRAELARRVRMVL 533

second phosphoacceptor receiver (REC) domain of Dictyostelium discoideum hybrid signal transduction histidine kinase D and similar domains; Dictyostelium discoideum hybrid signal transduction histidine kinase D (DhkD) is a large protein that contains two histidine kinase (HK) and two REC domains on the intracellular side of a single pass transmembrane domain, and extracellular PAS and PAC domains that likely are involved in ligand binding. This model represents the second REC domain and similar domains. DhkD activates the cAMP phosphodiesterase RegA to ensure proper prestalk and prespore patterning, tip formation, and the vertical elongation of the mound into a finger, in Dictyostelium discoideum. REC domains function as phosphorylation-mediated switches within response regulators, but some also transfer phosphoryl groups in multistep phosphorelays.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1501583231  14 ILVAEDDSILRPLLVELLDEMQFEVIAAEDGTKAMALLQDLdcnhmHVDLLLTDIGLPGVNGNKLAEFARKIWPNLSILF 93
Cdd:cd17580     1 ILVVDDNEDAAEMLALLLELEGAEVTTAHSGEEALEAAQRF-----RPDVILSDIGMPGMDGYELARRLRELPWLANTPA 75

                  ....*..
gi 1501583231  94 I--TGYA 98
Cdd:cd17580    76 IalTGYG 82

phosphoacceptor receiver (REC) domain of hybrid sensor histidine kinases/response regulators similar to Arabidopsis thaliana CKI1 and Escherichia coli RcsC; This family is composed of hybrid sensor histidine kinases/response regulators that are sensor histidine kinases (HKs) fused with a REC domain, similar to the sensor histidine kinase CKI1 from Arabidopsis thaliana, which is involved in multi-step phosphorelay (MSP) signaling that mediates responses to a variety of important stimuli in plants. MSP involves a signal being transferred from HKs via histidine phosphotransfer proteins (AHP1-AHP5) to nuclear response regulators. The CKI1 REC domain specifically interacts with the downstream signaling protein AHP2, AHP3 and AHP5. The plant MSP system has evolved from the prokaryotic two-component system (TCS), which allows organisms to sense and respond to changes in environmental conditions. This family also includes bacterial hybrid sensor HKs such as Escherichia coli RcsC, which is a component of the Rcs signalling pathway that controls a variety of physiological functions like capsule synthesis, cell division, and motility. REC domains function as phosphorylation-mediated switches within response regulators, but some also transfer phosphoryl groups in multistep phosphorelays.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1501583231  14 ILVAEDDSILRPLLVELLDEMQFEVIAAEDGTKAMALLQDldcnhMHVDLLLTDIGLPGVNGnklAEFARKI------WP 87
Cdd:cd17546     1 VLVVDDNPVNRKVLKKLLEKLGYEVDVAENGQEALELLKE-----EPFDLVLMDLQMPVMDG---LEATRRIreleggGR 72

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|....*....
gi 1501583231  88 NLSILFITGYA----------HGINtmtldnkiQLLTKPFSLGVLTKRI 126
Cdd:cd17546    73 RTPIIALTANAleedrekcleAGMD--------DYLSKPVKLDQLKEVL 113

phosphoacceptor receiver (REC) domain of chemotaxis protein CheV and similar proteins; This subfamily includes the REC domains of Bacillus subtilis chemotaxis protein CheV, Myxococcus xanthus gliding motility regulatory protein FrzE, and similar proteins. CheV is a hybrid protein with an N-terminal CheW-like domain and a C-terminal CheY-like REC domain. The CheV pathway is one of three systems employed by B. subtilis for sensory adaptation that contribute to chemotaxis. It is involved in the transmission of sensory signals from chemoreceptors to flagellar motors. Together with CheW, it is involved in the coupling of methyl-accepting chemoreceptors to the central two-component histidine kinase CheA. FrzE is a hybrid sensor histidine kinase/response regulator that is part of the Frz pathway that controls cell reversal frequency to support directional motility during swarming and fruiting body formation. REC domains function as phosphorylation-mediated switches within response regulators, but some also transfer phosphoryl groups in multistep phosphorelays.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1501583231  14 ILVAEDDSILRPLLVELLDEMQFEVIAAEDGTKAMALLQDLDCN----HMHVDLLLTDIGLPGVNGNKLAEFARKIwPNL 89
Cdd:cd19924     1 ILVVDDSPTARKQLRDLLKNLGFEIAEAVDGEEALNKLENLAKEgndlSKELDLIITDIEMPKMDGYELTFELRDD-PRL 79

                  ....*.
gi 1501583231  90 SILFIT 95
Cdd:cd19924    80 ANIPVI 85

DNA-binding response regulator, LytR/AlgR family [Transcription, Signal transduction mechanisms];

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1501583231  14 ILVAEDDSILRPLLVELLDEM-QFEVIA-AEDGTKAMALLQDLdcnhmHVDLLLTDIGLPGVNGNKLAEFARKIWPNLSI 91
Cdd:COG3279     4 ILIVDDEPLARERLERLLEKYpDLEVVGeASNGEEALELLEEH-----KPDLVFLDIQMPGLDGFELARQLRELDPPPPI 78

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|.
gi 1501583231  92 LFITGYA-HGINTMTLdNKIQLLTKPFSLGVLTKRIEELIS 131
Cdd:COG3279    79 IFTTAYDeYALEAFEV-NAVDYLLKPIDEERLAKALEKAKE 118

phosphoacceptor receiver (REC) domain of ArcA- and TorR-like OmpR family response regulators; This subfamily includes Escherichia coli TorR and ArcA, both OmpR family response regulators that mediate adaptation to changes in various respiratory growth conditions. The TorS-TorR two-component system (TCS) is responsible for the tight regulation of the torCAD operon, which encodes the trimethylamine N-oxide (TMAO) reductase respiratory system in response to anaerobic conditions and the presence of TMAO. The ArcA-ArcB TCS is involved in cell growth during anaerobiosis. ArcA is a global regulator that controls more than 30 operons involved in redox regulation (the Arc modulon). OmpR family DNA-binding response regulators are characterized by a REC domain and a winged helix-turn-helix (wHTH) DNA-binding output effector domain. REC domains function as phosphorylation-mediated switches within response regulators, but some also transfer phosphoryl groups in multistep phosphorelays.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1501583231  14 ILVAEDDSILRPLLVELLDEMQFEVIAAEDGTKAMALLQDldcnhMHVDLLLTDIGLPGVNGNKLAEFARKiWPNLSILF 93
Cdd:cd17619     3 ILIVEDEPVTRATLKSYFEQEGYDVSEAGDGEEMRQILAR-----QDIDLVLLDINLPGKDGLSLTRELRE-QSEVGIIL 76

                          90       100       110
                  ....*....|....*....|....*....|....*..
gi 1501583231  94 ITGYAHGIN-----TMTLDNKIqllTKPFSLGVLTKR 125
Cdd:cd17619    77 VTGRDDEVDrivglEIGADDYV---TKPFNPRELLVR 110

phosphoacceptor receiver (REC) domain of hydrogen uptake protein regulator (HupR) and similar domains; This family is composed of mostly uncharacterized response regulators with similarity to the REC domains of response regulator components of two-component systems that regulates hydrogenase activity, including HupR and HoxA. HupR is part of the HupT/HupR system that controls the synthesis of the membrane-bound [NiFe]hydrogenase, HupSL, of the photosynthetic bacterium Rhodobacter capsulatus. It contains an N-terminal REC domain, a central sigma-54 interaction domain that lacks ATPase activity, and a C-terminal DNA-binding domain. Members of this family contain a REC domain and various output domains including the cyclase homology domain (CHD) and the c-di-GMP phosphodiesterase domains, HD-GYP and EAL. REC domains function as phosphorylation-mediated switches within response regulators, but some also transfer phosphoryl groups in multistep phosphorelays.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1501583231  11 KKIILVAEDDSILRpLLVELLDEMQFEVIAAEDGTKAMALLQdldcnHMHVDLLLTDIGLPGVNGNKLAEFARKIWPN-L 89
Cdd:cd17569     1 PTILLVDDEPNILK-ALKRLLRREGYEVLTATSGEEALEILK-----QEPVDVVISDQRMPGMDGAELLKRVRERYPDtV 74

                  ....*....
gi 1501583231  90 SILfITGYA 98
Cdd:cd17569    75 RIL-LTGYA 82

phosphoacceptor receiver (REC) domain of citrate family two-component system response regulators; This family includes Lactobacillus paracasei MaeR, Escherichia coli DcuR and DpiA, Klebsiella pneumoniae CitB, as well as Bacillus DctR, MalR, and CitT. These are all response regulators of two-component systems (TCSs) from the citrate family, and are involved in the transcriptional regulation of genes associated with L-malate catabolism (MaeRK), citrate-specific fermentation (DpiAB, CitAB), plasmid inheritance (DpiAB), anaerobic fumarate respiratory system (DcuRS), and malate transport/utilization (MalKR). REC domains function as phosphorylation-mediated switches within response regulators, but some also transfer phosphoryl groups in multistep phosphorelays.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1501583231  14 ILVAEDDSILRPLLVELLDEM-QFEVIA-AEDGTKAMALLQDLdcnhmHVDLLLTDIGLPGVNGNKLAEFARKIWPNLSI 91
Cdd:cd19925     3 VLIVEDDPMVAEIHRAYVEQVpGFTVIGtAGTGEEALKLLKER-----QPDLILLDIYLPDGNGLDLLRELRAAGHDVDV 77

                          90       100       110
                  ....*....|....*....|....*....|....*...
gi 1501583231  92 LFITGYAH--GINTMTLDNKIQLLTKPFSLGVLTKRIE 127
Cdd:cd19925    78 IVVTAANDveTVREALRLGVVDYLIKPFTFERLRQRLE 115

two-component response regulator; Provisional

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1501583231  14 ILVAEDDSILRPLLVELLDEMQFEVIAAEDGTKAMALLQDLDCNhmhvdLLLTDIGLPGVNGNKLAEFARKIwPNLSILF 93
Cdd:PRK11173    6 ILIVEDELVTRNTLKSIFEAEGYDVFEATDGAEMHQILSENDIN-----LVIMDINLPGKNGLLLARELREQ-ANVALMF 79

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|....*....
gi 1501583231  94 ITGYahgintmtlDN---KI--------QLLTKPFSLGVLTKRIEELIS 131
Cdd:PRK11173   80 LTGR---------DNevdKIlgleigadDYITKPFNPRELTIRARNLLS 119

cheY-homologous receiver domain; CheY regulates the clockwise rotation of E. coli flagellar motors. This domain contains a phosphoacceptor site that is phosphorylated by histidine kinase homologues.

                           10        20        30        40        50
                   ....*....|....*....|....*....|....*....|....*....|....*...
gi 1501583231   14 ILVAEDDSILRPLLVELLDEMQFEVIAAEDGTKAMALLQDLdcnhmHVDLLLTDIGLP 71
Cdd:smart00448   3 ILVVDDDPLLRELLKALLEKEGYEVDEATDGEEALELLKEE-----KPDLILLDIMMP 55

phosphoacceptor receiver (REC) domain of nitrogen assimilation regulatory protein NtrX and similar proteins; NtrX is part of the two-component regulatory system NtrY/NtrX that is involved in the activation of nitrogen assimilatory genes such as Gln. It is phosphorylated by the histidine kinase NtrY and interacts with sigma-54. NtrX is a member of the NtrC family, characterized by a domain architecture containing an N-terminal REC domain, followed by a central sigma-54 interaction/ATPase domain, and a C-terminal DNA binding domain. NtrC family response regulators are sigma54-dependent transcriptional activators. Also included in this subfamily is Aquifex aeolicus NtrC4. The ability of the central domain to hydrolyze ATP and thus to interact effectively with a complex of RNA polymerase, sigma54, and promoter, is controlled by the phosphorylation status of the REC domain. REC domains function as phosphorylation-mediated switches within response regulators, but some also transfer phosphoryl groups in multistep phosphorelays.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1501583231  14 ILVAEDDSILRPLLVELLDEMQFEVIAAEDGTKAMALLQDLdcnhmHVDLLLTDIGLPGVNGNKLAEFARKIWPNLSILF 93
Cdd:cd17550     1 ILIVDDEEDIRESLSGILEDEGYEVDTAADGEEALKLIKER-----RPDLVLLDIWLPDMDGLELLKEIKEKYPDLPVIM 75

                          90       100       110
                  ....*....|....*....|....*....|....*..
gi 1501583231  94 ITGyaHGintmTLDNKIQ--------LLTKPFSLGVL 122
Cdd:cd17550    76 ISG--HG----TIETAVKatklgaydFIEKPLSLDRL 106

envelope stress response regulator transcription factor CpxR;

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....
gi 1501583231  12 KIILVaEDDSILRPLLVELLDEMQFEVIAAEDGTKAMALLQDldcnhmHVDLLLTDIGLPGVNG 75
Cdd:PRK10955    3 KILLV-DDDRELTSLLKELLEMEGFNVIVAHDGEQALDLLDD------SIDLLLLDVMMPKKNG 59

phosphoacceptor receiver (REC) domain of PhoB response regulator from the OmpR family; The transcription factor PhoB is a component of the PhoR/PhoB two-component system, a key regulatory protein network that facilitates response to inorganic phosphate (Pi) starvation conditions by turning on the phosphate (pho) regulon whose products are involved in phosphorus uptake and metabolism. PhoB is a member of the OmpR family of DNA-binding response regulators that contains REC and winged helix-turn-helix (wHTH) DNA-binding output effector domains. REC domains function as phosphorylation-mediated switches within response regulators, but some also transfer phosphoryl groups in multistep phosphorelays.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1501583231  14 ILVAEDDSILRPLLVELLDEMQFEVIAAEDGTKAMALLQDldcnhMHVDLLLTDIGLPGVNGNKLAEFARK--IWPNLSI 91
Cdd:cd17618     3 ILIVEDEPAIREMIAFNLERAGFDVVEAEDAESAVNLIVE-----PRPDLILLDWMLPGGSGIQFIRRLKRdeMTRDIPI 77

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|....*.
gi 1501583231  92 LFITGYAhgintmTLDNKIQLL--------TKPFSLGVLTKRIEEL 129
Cdd:cd17618    78 IMLTARG------EEEDKVRGLeagaddyiTKPFSPRELVARIKAV 117

pseudo receiver domain of pseudo-response regulators; In Arabidopsis, five pseudo-response regulators (PRRs), also called APRRs, comprise a core group of clock components that controls the pace of the central oscillator of the circadian clock, an endogenous time-keeping mechanism that enables organisms to adapt to external daily cycles. The coordinated sequential expression of PRR9 (APRR9), PRR7 (APRR7), PRR5 (APRR5), PRR3 (APRR3), and PRR1 (APRR1) results in circadian waves that may be at the basis of the endogenous circadian clock. PRRs contain an N-terminal pseudo receiver (psREC) domain that resembles the receiver domain of a two-component response regulator, but lacks an aspartate residue that accepts a phosphoryl group from the sensor kinase, and a CCT motif at the C-terminus that contains a putative nuclear localization signal. The psREC domain is involved in protein-protein interactions.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 1501583231  14 ILVAEDDSILRPLLVELLDEMQFEVIAAEDGTKAMALLQDLDcnhMHVDLLLTDIGLPGVNGNKL 78
Cdd:cd17582     1 VLLVENDDSTRQIVTALLRKCSYEVTAASDGLQAWDVLEDEQ---NEIDLILTEVDLPVSSGFKL 62

phosphoacceptor receiver (REC) domain of C4-dicarboxylic acid transport protein D (DctD) and similar proteins; C4-dicarboxylic acid transport protein D (DctD) is part of the two-component regulatory system DctB/DctD, which regulates C4-dicarboxylate transport via regulation of expression of the dctPQM operon and dctA. It is an activator of sigma(54)-RNA polymerase holoenzyme that uses the energy released from ATP hydrolysis to stimulate the isomerization of a closed promoter complex to an open complex capable of initiating transcription. DctD is a member of the NtrC family, characterized by a domain architecture containing an N-terminal REC domain, followed by a central sigma-54 interaction/ATPase domain, and a C-terminal DNA binding domain. The ability of the central domain to hydrolyze ATP and thus to interact effectively with a complex of RNA polymerase, sigma54, and promoter, is controlled by the phosphorylation status of the REC domain. REC domains function as phosphorylation-mediated switches within response regulators, but some also transfer phosphoryl groups in multistep phosphorelays.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1501583231  14 ILVAEDDSILRPLLVELLDEMQFEVIAAEDGTKAMALLQDlDCNhmhvDLLLTDIGLPGVNGNKLAEFARKIWPNLSILF 93
Cdd:cd17549     1 VLLVDDDADVREALQQTLELAGFRVRAFADAEEALAALSP-DFP----GVVISDIRMPGMDGLELLAQIRELDPDLPVIL 75

                  ....*..
gi 1501583231  94 ITGyaHG 100
Cdd:cd17549    76 ITG--HG 80

two-component system sensor histidine kinase RcsC;

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1501583231  14 ILVAEDDSILRPLLVELLDEMQFEVIAAEDGTKAMALLQDldcnhMHVDLLLTDIGLPGVNGNKLAEFARKIWPNLSILF 93
Cdd:PRK10841  804 ILVVDDHPINRRLLADQLGSLGYQCKTANDGVDALNVLSK-----NHIDIVLTDVNMPNMDGYRLTQRLRQLGLTLPVIG 878

                  ....*
gi 1501583231  94 ITGYA 98
Cdd:PRK10841  879 VTANA 883

phosphoacceptor receiver (REC) domain of nitrogen regulatory protein C 1 (NtrC1) from Aquifex aeolicus and similar NtrC family response regulators; NtrC family proteins are transcriptional regulators that have REC, AAA+ ATPase/sigma-54 interaction, and DNA-binding output domains. This subfamily of NtrC proteins include Aquifex aeolicus NtrC1 and Vibrio quorum-sensing signal integrator LuxO. The N-terminal REC domain of NtrC proteins regulate the activity of the protein and its phosphorylation controls the AAA+ domain oligomerization, while the central AAA+ domain participates in nucleotide binding, hydrolysis, oligomerization, and sigma54 interaction. REC domains function as phosphorylation-mediated switches within response regulators, but some also transfer phosphoryl groups in multistep phosphorelays.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1501583231  14 ILVAEDDSILRPLLVELLDEMQFEVIAAEDGTKAMALLQDldcnhMHVDLLLTDIGLPGVNGNKLAEFARKIWPNLSILF 93
Cdd:cd17572     1 VLLVEDSPSLAALYQEYLSDEGYKVTHVETGKEALAFLSD-----QPPDVVLLDLKLPDMSGMEILKWIQERSLPTSVIV 75

                          90       100
                  ....*....|....*....|....*....
gi 1501583231  94 ITgyAHG-----INTMTLdNKIQLLTKPF 117
Cdd:cd17572    76 IT--AHGsvdiaVEAMRL-GAYDFLEKPF 101

phosphoacceptor receiver (REC) domain of hydrogen uptake protein regulator (HupR); Members of this subfamily are response regulator components of two-component systems that regulates hydrogenase activity, including HupR and HoxA. HupR is part of the HupT/HupR system that controls the synthesis of the membrane-bound [NiFe]hydrogenase, HupSL, of the photosynthetic bacterium Rhodobacter capsulatus. It belongs to the nitrogen regulatory protein C (NtrC) family of response regulators, which activate transcription by RNA polymerase (RNAP) in response to a change in the environment. HupR is an unusual member of this family as it activates transcription when unphosphorylated, and transcription is inhibited by phosphorylation. Proteins in this subfamily contain an N-terminal REC domain, a central sigma-54 interaction domain that lacks ATPase activity, and a C-terminal DNA-binding domain. REC domains function as phosphorylation-mediated switches within response regulators, but some also transfer phosphoryl groups in multistep phosphorelays.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1501583231  14 ILVAEDDSILRPLLVELLDEmQFEVIAAEDGTKAMALLQDLDcnhmhVDLLLTDIGLPGVNGNKLAEFARKIWPNLSILF 93
Cdd:cd17596     3 ILVVDDEVRSLEALRRTLEE-DFDVLTAASAEEALAILEEEW-----VQVILCDQRMPGTTGVEFLKEVRERWPEVVRII 76

                          90       100
                  ....*....|....*....|....*.
gi 1501583231  94 ITGYAHGINTMTLDNKI---QLLTKP 116
Cdd:cd17596    77 ISGYTDSEDIIAGINEAgiyQYLTKP 102