Cloning and expression of the fbc operon encoding the FeS protein, cytochrome b and cytochrome c1 from the Rhodopseudomonas sphaeroides b/c1 complex.
The gene for the FeS protein of the Rhodopseudomonas sphaeroides b/c1 complex was identified by means of cross-hybridization with a segment of the gene encoding the corresponding FeS protein of Neurospora crassa. Plasmids (pRSF1-14) containing the cross-hybridizing region, covering in total 13.5 kb of chromosomal DNA, were expressed in vitro in a homologous system. One RSF plasmid directed the synthesis of all three main polypeptides of the R. sphaeroides b/c1 complex: the FeS protein, cytochrome b and cytochrome c1. The FeS protein and cytochrome c1 were apparently synthesized as precursor forms. None of the pRSF plasmids directed the synthesis of the 10-kd polypeptide found in b/c1 complex preparations. Partial sequencing of the cloned region was performed. Several sites of strong homology between R. sphaeroides and eukaryotic polypeptides of the b/c1 complex were identified. The genes encode the three b/c1 polypeptides in the order: (5') FeS protein, cytochrome b, cytochrome c1. The three genes are transcribed to give a polycistronic mRNA of 2.9 kb. This transcriptional unit has been designated the fbc operon; its coding capacity corresponds to the size of the polycistronic mRNA assuming that only the genes for the FeS protein (fbcF), cytochrome b (fbcB) and cytochrome c1 (fbcC) are present. This could indicate that these three subunits constitute the minimal catalytic unit of the b/c1 complex from photosynthetic membranes.
Gabellini
N
N
Harnisch
U
U
McCarthy
J E
JE
Hauska
G
G
Sebald
W
W
D002874:Chromosome Mapping; D003573:Cytochrome b Group / Q000235:genetics*; D003574:Cytochrome c Group / Q000235:genetics*; D004579:Electron Transport; D005786:Gene Expression Regulation; D005796:Genes; D005798:Genes, Bacterial; D007506:Iron-Sulfur Proteins / Q000235:genetics*; D046911:Macromolecular Substances; D008667:Metalloproteins / Q000235:genetics*; D009876:Operon; D010957:Plasmids; D012333:RNA, Messenger / Q000235:genetics; D012241:Rhodopseudomonas / Q000235:genetics*
D003573:Cytochrome b Group; D003574:Cytochrome c Group; D007506:Iron-Sulfur Proteins; D046911:Macromolecular Substances; D008667:Metalloproteins; D012333:RNA, Messenger