EC Number   |
General Information |
Reference |
|---|
   1.3.7.15 | evolution |
BciA (EC 1.3.1.75, NADPH-dependent C8 divinyl reductase) is a much faster and less energy consuming catalytic enzyme than the chlorophyllide oxidoreductase (COR). This finding implies that the bciA gene was acquired in each ancestral lineage by multiple horizontal gene transfer events after the establishment of anoxygenic photosynthesis. The high demand of Chl for large antenna complexes might have a major selective pressure for the evolutionary acquisition of an auxiliary divinyl reductase, BciA. Compared to the enzymatic activity of a-COR, BciA from Rhodobacter capsulatus has a lower affinity for DV-Chlide a but a much higher specific activity |
-, 763382 |
| 1.3.7.15 | evolution |
the light-independent chlorophyllide reductase BchXYZ is common to all anoxygenic phototrophic bacteria, including those with a type-I and those with a type-II photosynthetic reaction center. The phylogenetic analysis includes cultured phototrophic bacteria from several phyla, including Proteobacteria (138 species), Chloroflexi (five species), Chlorobi (six species), as well as Heliobacterium modesticaldum (Firmicutes), Chloracidobacterium acidophilum (Acidobacteria), and Gemmatimonas phototrophica (Gemmatimonadetes). Phylogenetic relationships based on a photosynthesis tree (PS tree, including sequences of PufHLM-BchXYZ) are compared with those of 16S rRNA gene sequences (RNS tree). Despite some significant differences, large parts are congruent between the 16S rRNA phylogeny and photosynthesis proteins. The phylogenetic relations demonstrate that bacteriochlorophyll biosynthesis had evolved in ancestors of phototrophic green bacteria much earlier as compared to phototrophic purple bacteria and that multiple events independently formed different lineages of aerobic phototrophic purple bacteria, many of which have very ancient roots. The Rhodobacterales clearly represent the youngest group, which is separated from other Proteobacteria by a large evolutionary gap |
-, 763455 |
| 1.3.7.15 | evolution |
the light-independent chlorophyllide reductase BchXYZ is common to all anoxygenic phototrophic bacteria, including those with a type-I and those with a type-II photosynthetic reaction center. The phylogenetic analysis includes cultured phototrophic bacteria from several phyla, including Proteobacteria (138 species), Chloroflexi (five species), Chlorobi (six species), as well as Heliobacterium modesticaldum (Firmicutes), Chloracidobacterium thermophilum (representative of Acidobacteria phylum), and Gemmatimonas phototrophica (Gemmatimonadetes). Phylogenetic relationships based on a photosynthesis tree (PS tree, including sequences of PufHLM-BchXYZ) are compared with those of 16S rRNA gene sequences (RNS tree). Despite some significant differences, large parts are congruent between the 16S rRNA phylogeny and photosynthesis proteins. The phylogenetic relations demonstrate that bacteriochlorophyll biosynthesis had evolved in ancestors of phototrophic green bacteria much earlier as compared to phototrophic purple bacteria and that multiple events independently formed different lineages of aerobic phototrophic purple bacteria, many of which have very ancient roots. The Rhodobacterales clearly represent the youngest group, which is separated from other Proteobacteria by a large evolutionary gap |
763455 |
| 1.3.7.15 | metabolism |
bacteriochlorophyll a (BChl) is an essential pigment for anoxygenic photosynthesis. In late steps of the BChl biosynthesis of Rhodobacter capsulatus, the C8 vinyl group and C7=C8 double bond of 8-vinyl chlorophyllide a (8 V-Chlide) are reduced by a C8 vinyl reductase (8VR), BciA (EC 1.3.1.75) or BciB (EC 1.3.7.13), and a nitrogenase-like enzyme, chlorophyllide a oxidoreductase (COR), respectively, to produce 3-vinyl-bacteriochlorphyllide a. BciB is a FAD-containing FeS protein that uses reduced ferredoxin as the reductant for the 8-vinyl reduction of 8 V-Chlide or 8 V-PChlide, while BciA utilizes NADPH |
-, 762912 |
| 1.3.7.15 | metabolism |
the biosynthesis of all bacteriochlorophylls involves the two-electron reduction of the C7-C8 double bond of the green pigment chlorophyllide, which is catalyzed by the nitrogenase-like two-component metalloenzyme chlorophyllide oxidoreductase (COR), whereas in all methanogenic microbes, another nitrogenase-like system, CfbC/D, is responsible for the sophisticated six-electron reduction of Ni2+-sirohydrochlorin a,c-diamide in the course of coenzyme F430 biosynthesis |
-, 763435 |
| 1.3.7.15 | physiological function |
bacteriochlorophyll a (BChl) is an essential pigment for anoxygenic photosynthesis. In late steps of the BChl biosynthesis of Rhodobacter capsulatus, the C8 vinyl group and C7=C8 double bond of 8-vinyl chlorophyllide a (8 V-Chlide) are reduced by a C8 vinyl reductase (8VR), BciA (EC 1.3.1.75) or BciB (EC 1.3.7.13), and a nitrogenase-like enzyme, chlorophyllide a oxidoreductase (COR), respectively, to produce 3-vinyl-bacteriochlorphyllide a. The COR activity can act as a third 8VR, confirmed in vivo by the loss of 8VR activity mutants lacking bciA and genes encoding subunits of COR. In contrast to BciA and BciB, COR is a nitrogenase-like complex enzyme consisting of two separable components, the X protein (a BchX dimer) and the YZ protein (a BchY-BchZ heterotetramer). The X protein serves as the reductase component by transferring electrons from a [4Fe-4S] cluster held in the interface between the BchX homodimer and the YZ protein. The YZ protein is the catalytic component, as it accepts electrons from the X protein and transfers them to the Chlide substrate via a [4Fe-4S] cluster, to produce 3-vinyl bacteriochlorophyllide a (3 V-BChlide). 3 V-BChlide is produced via Chlide rather than via 3,8-divinyl BChlide (81,82-didehydro-3 V-BChlide) |
-, 762912 |
| 1.3.7.15 | physiological function |
chlorophyllide (Chlide) oxidoreductase, COR, is a unique BChl biosynthesis enzyme which shows distinct substrate recognition and hydrogen addition activities, depending on the host strain. COR in BChl a-producing phototrophic bacteria (a-COR) catalyzes the C7=C8 double bond reduction of Chlide a, whereas COR in BChl b- and BChl g-producing bacteria (b/g-COR) forms the C8-ethylidene group using DV-Chlide a as the substrate. Chlorophyllide oxidoreductase (COR) reduces the C7=C8 double bond of chlorophyllide a (Chlide a) bearing the C8-ethyl group, but also potentially catalyzes the reduction of the C8-vinyl group of divinyl-chlorophyllide a (DV-Chlide a). DV-Chlide a is a universal precursor for chlorophyll or bacteriochlorophyll biosynthesis in all photosynthetic organisms |
-, 763382 |
| 1.3.7.15 | physiological function |
heterologous expression of subunits bchXYZ in Synechocystis sp. PCC6803 results in decrease in photosynthetic growth. An increase in cytosolic superoxide dismutase level in the recombinant Synechocystis sp. PCC6803 completely reversed the growth cessation, demonstraing that chlorophyllide a reductase generates superoxide in Synechocystis sp. PCC6803 |
-, 727511 |
| 1.3.7.15 | physiological function |
the bchA locus contains three genes bchX, Y and Z, which are essential for the reduction of 2-devinyl-2-hydroxyethyl chlorophyllide a. BchX may supply electrons for reduction of 2-devinyl-2-hydroxyethyl chlorophyllide a |
-, 728309 |
| 1.3.7.15 | physiological function |
the biosynthesis of all bacteriochlorophylls involves the two-electron reduction of the C7-C8 double bond of the green pigment chlorophyllide, which is catalyzed by the nitrogenase-like two-component metalloenzyme chlorophyllide oxidoreductase (COR), whereas in all methanogenic microbes, another nitrogenase-like system, CfbC/D, is responsible for the sophisticated six-electron reduction of Ni2+-sirohydrochlorin a,c-diamide in the course of coenzyme F430 biosynthesis |
-, 763435 |
