Heme oxygenase [Coenzyme transport and metabolism];

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 74213396  11 QDLSEALKEATKEVHIQAENAEFMKNFQKGQVSREGFKLVMASLYHIYTALEEEIERNKQNPVYAPLYFPeELHRRAALE 90
Cdd:COG5398   1 SPLSTALREGTAKAHTAAENSGFMKALLKGRLDRDAYVALLAQLYFVYSALEEALERHRDHPVVGPFYFP-ELNRLPALE 79

                ....*.
gi 74213396  91 HfDIRF 96
Cdd:COG5398  80 A-DLAF 84

heme oxygenase; Provisional

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 74213396    9 MPQDLSEALKEATKEVHIQAENAEFMKNFQKGQVSREGFKLVMASLYHIYTALEEEIERNKQNPVYAPLYFPeELHRRAA 88
Cdd:CHL00168   1 MVTNLATQLREGTTKSHSMAENVSFVKSFLGGVIDKKSYRKLVANLYFVYSAIEEEIEKNKEHPLIKPIYFQ-ELNRKES 79

                 ..
gi 74213396   89 LE 90
Cdd:CHL00168  80 LE 81

Heme oxygenase [Coenzyme transport and metabolism];

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 74213396  11 QDLSEALKEATKEVHIQAENAEFMKNFQKGQVSREGFKLVMASLYHIYTALEEEIERNKQNPVYAPLYFPeELHRRAALE 90
Cdd:COG5398   1 SPLSTALREGTAKAHTAAENSGFMKALLKGRLDRDAYVALLAQLYFVYSALEEALERHRDHPVVGPFYFP-ELNRLPALE 79

                ....*.
gi 74213396  91 HfDIRF 96
Cdd:COG5398  80 A-DLAF 84

heme oxygenase in eukaryotes and some bacteria; This subfamily contains heme oxygenase (HO, EC 1.14.14.18) found in eukaryotes as well as some proteobacteria, including cyanobacteria. Heme oxygenase (HO) catalyzes the rate limiting step in the degradation of heme to biliverdin in a multi-step reaction. HO is essential for recycling of iron from heme which is used as a substrate and cofactor for its own degradation to biliverdin, iron, and carbon monoxide. In vertebrates, HO plays a role in heme homeostasis and oxidative stress response, and cellular signaling in mammals that include isoforms HO-1, HO-2 and HO-3. HO-1 is ubiquitously expressed after induction while HO-2 expression is constitutive, mostly limited to certain organs, such as the brain, testes, and the vascular system. HO-3 is non-functional in humans, suggesting that the Hmox3 gene is a pseudogene derived from HO-2 transcripts. In higher plants and cyanobacteria, heme oxygenase is required for the synthesis of light-harvesting pigments, which contain tetrapyrrols derived from biliverdin. Candida albicans expresses a heme oxygenase that is required for the utilization of heme as a nutritional iron source, whereas Saccharomyces cerevisiae responds to iron deprivation by increasing Hmx1p transcription, which is controlled by the major iron-dependent transcription factor, Aft1p, and promotes both the re-utilization of heme iron and the regulation of heme-dependent transcription during periods of iron scarcity. In pathogenic bacteria, HO is part of a pathway for iron acquisition from host heme. In Leptospira interrogans, a pathogenic spirochete that causes leptospirosis, HO is required for iron utilization when hemoglobin is the sole iron source, thus making HO an interesting target for novel antimicrobial agents. HO shares tertiary structure similarity to methane monooxygenase (EC 1.14.13.25), ribonucleotide reductase (EC 1.17.4.1) and thiaminase II (EC 3.5.99.2), but shares little sequence homology.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 74213396  12 DLSEALKEATKEVHIQAENAEFMKNFQKGQVSREGFKLVMASLYHIYTALEEEIERNKQNPVYAPLYFPEELHRRAALEH 91
Cdd:cd19165   1 PLSERLREATRKLHTAAERSIFAKLLLAGPLDREAYARLLVQLYFVYEALEEALDRLADDPVLAAALYDPELERSEALEA 80

                ....*
gi 74213396  92 fDIRF 96
Cdd:cd19165  81 -DLAF 84

heme oxygenase found in pathogenic bacteria; This subfamily contains bacterial heme oxygenase (HO, EC 1.14.14.18), where HO is part of a pathway for iron acquisition from host heme and heme products. Most of these proteins have yet to be characterized. HO catalyzes the rate limiting step in the degradation of heme to biliverdin in a multi-step reaction. HO is essential for recycling of iron from heme which is used as a substrate and cofactor for its own degradation to biliverdin, iron, and carbon monoxide. This family includes heme oxygenase (pa-HO) from Pseudomonas aeruginosa, an opportunistic pathogen that causes a variety of systemic infections, particularly in those afflicted with cystic fibrosis, as well as cancer and AIDS patients who are immunosuppressed. Pa-HO, expressed by the PigA gene, is critical for the acquisition of host iron since there is essentially no free iron in mammals, and is unusual since it hydroxylates heme predominantly at the delta-meso heme carbon, while all other well-studied HOs hydroxylate the alpha-meso carbon. Also included in this family is Neisseria meningitidis HO which is substantially different from the human HO, with the reaction product being ferric biliverdin IXalpha rather than reduced iron and free biliverdin IXalpha. HO shares tertiary structure similarity to methane monooxygenase (EC 1.14.13.25), ribonucleotide reductase (EC 1.17.4.1) and thiaminase II (EC 3.5.99.2), but shares little sequence homology.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 74213396  13 LSEALKEATKEVHIQAENAeFMknFQKGQVSREGFKLVMASLYHIYTALEEEIERNKQNPVYAPLyfpEELHRRAALEHf 92
Cdd:cd19166   1 LRARLRAATRAAHERLEAL-LG--LLDLFLTLADYARFLAAQYGFYAPLEAALAAALLAALLPDL---AARRRLPLLAA- 73

                ...
gi 74213396  93 DIR 95
Cdd:cd19166  74 DLA 76