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KMID : 0613820060160040632
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Journal of Life Science
2006 Volume.16 No. 4 p.632 ~ p.639
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Regulation of Photosynthesis Genes ( puf, puc, puhA, bchC, bchE, bchF, and bchI) in Rhodobacter sphaeroides
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Ko In-Jeong
Kim Yong-Jin
Lee Jin-Mok
Shin Sun-Joo
Oh Jeong-Il
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Abstract
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Here we examined the expression patterns and regulation of seven photosynthesis (PS) genes (puf, puc, puhA, bchC, bchE, bchF, and bchI) in the anoxygenic photosynthetic bacterium, Rhodobacter sphaeroides, based on lacZ reporter gene assay. Expression of the tested PS genes, except puhA and bchI, were strongly induced in R. sphaeroides grown under anaerobic conditions relative to that under aerobic conditions. The puhA and bchI genes appear to form the operons together with bchFNBHLM-RSP0290 and crtA, respectively. Expression of the puf, puc, and bchCXYZ operons in R. sphaeroides grown photosynthetically was proportional to the incident light intensity, whereas that of bchFNBHLM(RSP0290-puhA) was inversely related to light intensity. Expression of bchEJG was lowest under medium-light photosynthetic conditions (10 W/㎡) and highest under high light conditions (100 W/㎡). The regulation of PS genes by the three major regulatory systems involved in oxygen- and light-sensing in R. sphaeroides is as following: puf and bchC are regulated by both the PpsR repressor and the PrrBA two-component system. The puc operon is under control of PpsR, FnrL, and PrrBA system. Expression of bchE is controlled by FnrL and PrrBA two-component system, whereas bchF is regulated exclusively by PpsR. It was demonstrated that the PpsR repressor is responsible for high-light repression of bchF and that FnrL might be involved in perceiving the cellular redox state in addition to sensing O² itself.
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KEYWORD
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FnrL, photosynthesis gene, PrrBA two-component system, PpsR repressor, redox sensing, Rhodobacter sphaeroides
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