Organization and expression of photosynthesis genes and operons in anoxygenic photosynthetic proteobacteria.
Genes belonging to the same metabolic route are usually organized in operons in microbial genomes. For instance, most genes involved in photosynthesis were found clustered and organized in operons in photosynthetic Alpha- and Betaproteobacteria. The discovery of Gammaproteobacteria with a conserved photosynthetic gene cluster revives the questions on the role and the maintenance of such organization in proteobacteria. In this paper, we report the analysis of the structure and expression of the 14 kb cluster (crtEF-bchCXYZ-pufBALMC-crtADC) in the photosynthetic betaproteobacterium Rubrivivax gelatinosus, with the purpose of understanding the reasons and the biological constraints that might have led to the clustering of photosynthesis genes. The genetic analyses are substantiated by reverse transcription-PCR data which reveal the presence of a transcript encompassing the 14 genes and provide evidence of a polycistronic 'super-operon' organization starting at crtE and ending 14 kb downstream at the crtC gene. Furthermore, genetic analyses suggest that one of the selection pressures that may have driven and maintained the photosynthesis operons/super-operons in proteobacteria could very likely be the coexpression and regulation of the clustered genes/operon.
Liotenberg
Sylviane
S
CNRS, Centre de Génétique Moléculaire, UPR 2167, Gif-sur-Yvette, F-91198, France.
Steunou
Anne-Soisig
AS
Picaud
Martine
M
Reiss-Husson
Françoise
F
Astier
Chantal
C
Ouchane
Soufian
S
D000332:Aerobiosis; D001426:Bacterial Proteins / Q000235:genetics; D020562:Betaproteobacteria / Q000235:genetics* / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D002874:Chromosome Mapping; D015870:Gene Expression; D023061:Gene Order; D005798:Genes, Bacterial; D005810:Multigene Family; D009154:Mutation; D009876:Operon; D010101:Oxygen Consumption; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics*; D052817:Phototrophic Processes; D010860:Pigments, Biological / Q000096:biosynthesis; D010957:Plasmids; D011401:Promoter Regions, Genetic; D012329:RNA, Bacterial / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
D001426:Bacterial Proteins; D045322:Photosynthetic Reaction Center Complex Proteins; D010860:Pigments, Biological; D012329:RNA, Bacterial