title: Expression of the cbbLcbbS and cbbM genes and distinct organization of the cbb Calvin cycle structural genes of Rhodobacter capsulatus.
abstract: Rhodobacter capsulatus fixes CO2 via the Calvin reductive pentose phosphate pathway and, like some other nonsulfur purple bacteria, is known to synthesize two distinct structural forms of ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO). Cosmid clones that hybridized to form I (cbbLcbbS) and form II (cbbM) RubisCO gene probes were isolated from a genomic library of R. capsulatus strain SB1003. Southern blotting and hybridization analysis with gene-specific probes derived from Rhodobacter sphaeroides revealed that R. capsulatus cbbM is clustered with genes encoding other enzymes of the Calvin cycle, including fructose 1,6/sedoheptulose 1,7-bisphosphatase (cbbF), phosphoribulokinase (cbbP), transketolase (cbbT), glyceraldehyde-3-phosphate dehydrogenase (cbbG), and fructose 1,6-bisphosphate aldolase (cbbA), as well as a gene (cbbR) encoding a divergently transcribed LysR-type regulatory protein. Surprisingly, a cosmid clone containing the R. capsulatus form I RubisCO genes (cbbL and cbbS) failed to hybridize to the other cbb structural gene probes, unlike the situation with the closely related organism R. sphaeroides. The form I and form II RubisCO genes were cloned into pUC-derived vectors and were expressed in Escherichia coli to yield active recombinant enzyme in each case. Complementation of a RubisCO-deletion strain of R. sphaeroides to photosynthetic growth by R. capsulatus cbbLcbbS or cbbM was achieved using the broad host-range vector, pRK415, and R. sphaeroides expression vector pRPS-1.
authors.affiliation: Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA.
authors.forename: G C
authors.initials: GC
authors.lastname: Paoli
authors.forename: N S
authors.initials: NS
authors.lastname: Morgan
authors.forename: F R
authors.initials: FR
authors.lastname: Tabita
authors.forename: J M
authors.initials: JM
authors.lastname: Shively
mesh_terms: D002874:Chromosome Mapping; D003001:Cloning, Molecular; D003360:Cosmids; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D005810:Multigene Family; D010427:Pentose Phosphate Pathway / Q000235:genetics*; D016354:Rhodobacter capsulatus / Q000235:genetics* / Q000378:metabolism*; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics
chemical_list: D012273:Ribulose-Bisphosphate Carboxylase