Regulation of aerobic photosystem synthesis in the purple bacterium Rhodospirillum centenum by CrtJ and AerR.
Genes coding for putative CrtJ and AerR homologs were identified and characterized in the purple photosynthetic bacterium Rhodospirillum centenum (also known as Rhodocista centenaria), an organism that synthesizes photopigments even under highly aerated conditions. Mutational analysis indicated that in Rsp. centenum, gene crtJ codes for a repressor for photosynthesis gene expression as in Rhodobacter capsulatus, which exhibits a high level of oxygen repression of photosystem synthesis. In contrast to Rba. capsulatus, AerR in Rsp. centenum appears to be an aerobic activator; an aerR mutation resulted in significantly reduced levels of photopigment synthesis. Both aerR and crtJ mutants retained essentially normal levels of photosystem synthesis under anaerobic conditions, indicating that their activities are specific for aerobic photosystem synthesis. The readthrough transcript from crtE promoter, which is regulated by AerR and CrtJ, seems to be significant in maintaining the expression levels of the light harvesting I (puf) genes in Rsp. centenum. We suggest that AerR and CrtJ regulate aerobic photosystem synthesis primarily through controlling activity of the transcriptional readthrough.
Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, 226-8501, Japan. shmasuda@bio.titech.ac.jp
Shinji
S
Masuda
James
J
Berleman
Ben M
BM
Hasselbring
Carl E
CE
Bauer
D000332:Aerobiosis; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D015964:Gene Expression Regulation, Bacterial; D009154:Mutation; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D042182:Rhodospirillum centenum / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D014158:Transcription, Genetic / Q000235:genetics
D001426:Bacterial Proteins; D045322:Photosynthetic Reaction Center Complex Proteins