Gen name | Enzyme name | Functional groups sensitive to oxygen |
---|---|---|
bchI bchD bchH | Mg-chelatase | BchH contains the particular cystein motif CX2CX3CX14C, which coordinates a [4Fe - 4S] - cluster. This iron - sulfur cluster is particularly sensitive to oxygen and is transformed to a [3Fe - 4S] cluster in its presence. [78]. |
bchM | Mg-PPIX-O-methyltransferase | The methyl group is supplied by S - adenosyl - methionine. The oxygen - sensitive BchH has been proposed to be the substrate - binding protein of BchM [79, 80] |
bchE | Mg - PPIX - O - CH3 oxidative cyclase | BchE contains a conserved CX3CX2C cystein motif, which coordinates an oxygen - sensitive [4Fe - 4S] - cluster [77]. |
bchL bchN bchB | Dark allowed protochlorophyllide oxidoreductase (DPOR) | The reductase component BchL contains two conserved cysteine residues and the BchL- dimer coordinates an oxygen - sensitive [4Fe - 4S]-cluster [89]. The catalytic component (BchN-BchB)2 also contains conserved cysteines, which coordinate [4Fe - 4S]-clusters, however these are not oxygen-sensitive [129] |
bchX bchY bchZ | Chlorin reductase (COR) | BchX, BchY and BchZ are enzyme subunits structurally and functionally similar to BchL, BchN, and BchB, respectively [90, 91]. It has been shown that the subunit dimers (BchL)2 and (BchX)2 of DPOR and COR, respectively, which drive electrons to the substrates of these enzymes, are exposed to the cytoplasm [91, 92], i.e. to selenite and to the ROS produced during selenite reduction. |