D1, D2 subunits of photosystem II (PSII); M, L subunits of bacterial photosynthetic reaction center; This protein superfamily contains the D1, D2 subunits of the photosystem II (PS II) and the M, L subunits of the bacterial photosynthetic reaction center (RC). These four proteins are highly homologous and share a common fold. PS II is a multi-subunit protein found in the photosynthetic membranes of plants, algae, and cyanobacteria. It utilizes light-induced electron transfer and water-splitting reactions to produce protons, electrons, and molecular oxygen. The protons generated are instrumental in ATP formation. Bacterial photosynthetic reaction center (RC) complex is found in photosynthetic bacteria, such as purple bacteria and other proteobacteria species. It couples light-induced electron transfer to proton pumping across the membrane by reactions of a quinone molecule (QB) that binds two electrons and two protons at the active site. Protons are translocated from the bacterial cytoplasm to the periplasmic space, generating an electrochemical gradient of protons (the protonmotive force) that can be used to power reactions such as the synthesis of ATP.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 325168179    2 LFYNPFHMLSIAFLYGSALLFAMHGATILAVGRYGGEREIEQIVDRGTASERAGLFWRWTMGFNATMESIHRWAWWF 78
Cdd:TIGR01115 196 LYYNPFHMLSIAFLYGSALLFAMHGATILAVSRFGGDRELEQITDRGTAAERAALFWRWTMGFNATMESIHRWAWWF 272

photosynthetic reaction center M subunit; This model decribes the photosynthetic reaction center M subunit in non-oxygenic photosynthetic bacteria. Reaction center is an integral membrane pigment-protein that carries out light-driven electron transfer reactions. At the core of reacion center is a collection light-harvesting cofactors and closely associated polypeptides. The core protein complex is made of L, M and H subunits. The common cofactors include bacterichlorophyll, bacteriopheophytins, ubiquinone and no-heme ferrous iron. The net result of electron tranfer reactions is the establishment of proton electrochemical gradient and production of reducing equivalents in form of NADH. Ultimately the process results in the reduction of C02 to carbohydrates(C6H12O6) In non-oxygenic organisms, the electron donor is some organic acid and not water. Much of our current functional understanding of photosynthesis comes from the structural determination, spectroscopic studies and mutational analysis on the reaction center of Rhodobacter sphaeroides. [Energy metabolism, Electron transport, Energy metabolism, Photosynthesis]

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 325168179    2 LFYNPFHMLSIAFLYGSALLFAMHGATILAVGRYGGEREIEQIVDRGTASERAGLFWRWTMGFNATMESIHRWAWWF 78
Cdd:TIGR01115 196 LYYNPFHMLSIAFLYGSALLFAMHGATILAVSRFGGDRELEQITDRGTAAERAALFWRWTMGFNATMESIHRWAWWF 272

Subunit M of bacterial photosynthetic reaction center; Bacterial photosynthetic reaction center (RC) complex, subunit M. The bacterial photosynthetic reaction center couples light-induced electron transfer with pumping protons across the membrane using reactions involving a quinone molecule (QB) that binds two electrons and two protons at the active site. The reaction center consists of three membrane-bound subunits, designated L, M, and H, plus an additional extracellular cytochrome subunit. The L and M subunits are arranged around an axis of 2-fold rotational symmetry perpendicular to the membrane, forming a scaffold that maintains the cofactors in a precise configuration. The L and M subunits have both sequence and structural similarity, suggesting a common evolutionary origin. The L and M subunits bind noncovalently to the nine cofactors in 2-fold symmetric branches: four bacteriochlorophylls (Bchl), two bacteriopheophytins (Bphe), two ubiquinone molecules (QA and QB), and a non-heme iron. Two Bchls on the periplasmic side of the membrane form the 'special pair' or dimer which is the primary electron donor for the photosynthetic reactions. The electron transfer reaction proceeds from the dimer to an intermediate acceptor (PA), a primary quinone (QA), and a secondary quinone (QB). Protons are translocated from the bacterial cytoplasm to the periplasmic space, generating an electrochemical gradient of protons (the protonmotive force) that can be used to power reactions such as ATP synthesis. The RC complex is found in photosynthetic bacteria, such as purple bacteria and other proteobacteria species.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 325168179   2 LFYNPFHMLSIAFLYGSALLFAMHGATILAVGRYGGEREIEQIVDRGTASERAGLFWRWTMGFNATMESIHRWAWWF 78
Cdd:cd09291  185 FYYNPFHMLSIAFLYGSTLLFAMHGATILAVSRFGGEREIEQITDRGTATERAQLFWRWTMGFNATMESIHRWAWWF 261

bifunctional photosynthetic reaction center subunit L/M; Provisional

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 325168179   2 LFYNPFHMLSIAFLYGSALLFAMHGATILAVGRYGGEREIEQIVDRGTASERAGLFWRWTMGFNATMESIHRWAWWF 78
Cdd:PRK14505 519 FYYNPFHMLSIFFLLGSTLLLAMHGATIVATSKWKSEMEFTEMMAEGPGTQRAQLFWRWVMGWNANSYNIHIWAWWF 595

photosynthetic reaction center M subunit; This model decribes the photosynthetic reaction center M subunit in non-oxygenic photosynthetic bacteria. Reaction center is an integral membrane pigment-protein that carries out light-driven electron transfer reactions. At the core of reacion center is a collection light-harvesting cofactors and closely associated polypeptides. The core protein complex is made of L, M and H subunits. The common cofactors include bacterichlorophyll, bacteriopheophytins, ubiquinone and no-heme ferrous iron. The net result of electron tranfer reactions is the establishment of proton electrochemical gradient and production of reducing equivalents in form of NADH. Ultimately the process results in the reduction of C02 to carbohydrates(C6H12O6) In non-oxygenic organisms, the electron donor is some organic acid and not water. Much of our current functional understanding of photosynthesis comes from the structural determination, spectroscopic studies and mutational analysis on the reaction center of Rhodobacter sphaeroides. [Energy metabolism, Electron transport, Energy metabolism, Photosynthesis]

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 325168179    2 LFYNPFHMLSIAFLYGSALLFAMHGATILAVGRYGGEREIEQIVDRGTASERAGLFWRWTMGFNATMESIHRWAWWF 78
Cdd:TIGR01115 196 LYYNPFHMLSIAFLYGSALLFAMHGATILAVSRFGGDRELEQITDRGTAAERAALFWRWTMGFNATMESIHRWAWWF 272

Subunit M of bacterial photosynthetic reaction center; Bacterial photosynthetic reaction center (RC) complex, subunit M. The bacterial photosynthetic reaction center couples light-induced electron transfer with pumping protons across the membrane using reactions involving a quinone molecule (QB) that binds two electrons and two protons at the active site. The reaction center consists of three membrane-bound subunits, designated L, M, and H, plus an additional extracellular cytochrome subunit. The L and M subunits are arranged around an axis of 2-fold rotational symmetry perpendicular to the membrane, forming a scaffold that maintains the cofactors in a precise configuration. The L and M subunits have both sequence and structural similarity, suggesting a common evolutionary origin. The L and M subunits bind noncovalently to the nine cofactors in 2-fold symmetric branches: four bacteriochlorophylls (Bchl), two bacteriopheophytins (Bphe), two ubiquinone molecules (QA and QB), and a non-heme iron. Two Bchls on the periplasmic side of the membrane form the 'special pair' or dimer which is the primary electron donor for the photosynthetic reactions. The electron transfer reaction proceeds from the dimer to an intermediate acceptor (PA), a primary quinone (QA), and a secondary quinone (QB). Protons are translocated from the bacterial cytoplasm to the periplasmic space, generating an electrochemical gradient of protons (the protonmotive force) that can be used to power reactions such as ATP synthesis. The RC complex is found in photosynthetic bacteria, such as purple bacteria and other proteobacteria species.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 325168179   2 LFYNPFHMLSIAFLYGSALLFAMHGATILAVGRYGGEREIEQIVDRGTASERAGLFWRWTMGFNATMESIHRWAWWF 78
Cdd:cd09291  185 FYYNPFHMLSIAFLYGSTLLFAMHGATILAVSRFGGEREIEQITDRGTATERAQLFWRWTMGFNATMESIHRWAWWF 261

Photosystem II reaction center D1, PsbA [Energy production and conversion]; Photosystem II reaction center D1, PsbA is part of the Pathway/BioSystem: Photosystem II

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 325168179   2 LFYNPFHMLSIAFLYGSALLFAMHGATILAV-------------GRYGGEREIEQIVDRGTASERAGLFWRWTMGFNAtm 68
Cdd:COG5716  195 ILMNPFHMLGVAGVYGGALLFAMHGSLVTSVlrrettesesinaGYFGGQRELTYIVDRGTAGERARLFWRWTMGFNA-- 272

                         90
                 ....*....|.
gi 325168179  69 ESIHRWAWWFP 79
Cdd:COG5716  273 RSIHFWLAAFP 283

bifunctional photosynthetic reaction center subunit L/M; Provisional

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 325168179   2 LFYNPFHMLSIAFLYGSALLFAMHGATILAVGRYGGEREIEQIVDRGTASERAGLFWRWTMGFNATMESIHRWAWWF 78
Cdd:PRK14505 519 FYYNPFHMLSIFFLLGSTLLLAMHGATIVATSKWKSEMEFTEMMAEGPGTQRAQLFWRWVMGWNANSYNIHIWAWWF 595

bifunctional photosynthetic reaction center subunit L/M; Provisional

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 325168179   2 LFYNPFHMLSIAFLYGSALLFAMHGATILAVGRyggereieqivdRGTASERAGLFWRWTMGFNATMESIHRWAWW 77
Cdd:PRK14505 206 FFYNPFHAIGITLLFASTLFLHMHGSAVLSEAK------------RNISDQNIHVFWRNILGYSIGEIGIHRVAFW 269

D2 subunit of photosystem II (PS II); Photosystem II (PS II), D2 subunit. PS II is a multi-subunit protein found in the photosynthetic membranes of plants, algae, and cyanobacteria. It utilizes light-induced electron transfer and water-splitting reactions to produce protons, electrons, and molecular oxygen. The protons generated are instrumental in ATP formation. Molecular dioxygen is released as a by-product. PS II can be described as containing two parts: the photochemical part and the catalytic part. The photochemical portion promotes the fast, efficient light-induced charge separation and stabilization that occur when light is absorbed by chlorophyll. The catalytic portion, where water is oxidized, involves a cluster of Mn ions close to a redox-active tyrosine residue. The Mn cluster and its ligands form a functional unit called the oxygen-evolving complex (OEC) or the water-oxidizing complex (WOC). The D1 and D2 subunits are a pair of intertwined polypeptides. They contain all the cofactors involved directly in water oxidation and plastoquinone reduction. D1 and D2 are highly homologous and are also similar to the L and M proteins in bacterial photosynthetic reaction centers.

                         10        20
                 ....*....|....*....|....*
gi 325168179   5 NPFHMLSIAFLYGSALLFAMHGATI 29
Cdd:cd09288  181 NPFHMMGVAGVLGAALLCAIHGATV 205