DNA binding of wild type RegA protein and its differential effect on the expression of pigment binding proteins in Rhodobacter capsulatus.
The transcription of genes encoding pigment binding proteins in the facultative photosynthetic bacterium Rhodobacter capsulatus is regulated in response to oxygen partial pressure. Previous results identified RegA and RegB as members of a two component system involved in oxygen dependent synthesis of the photosynthetic apparatus. Here we demonstrate that RegA differentially controls the transcription of the puf and pucoperons which encode proteins of the LHI and LHII antenna complexes, respectively. In a regA mutant strain the level of puf specific mRNA reaches about 30% of the wild type levels and transcription is still responsive to oxygen tension. In contrast, the level of puc specific mRNA is very low and is no longer oxygen regulated. RegA binds to DNA sequences upstream of both the puf and puc operons, although with different affinities. We provide experimental evidence that a putative helix-turn-helix motif in the C-terminal region of RegA is responsible for its specific binding to the puf and puc promoter regions. In contrast to many other response regulators, the affinity of RegA for the target DNA is only slightly modified by phosphorylation.
Institut für Mikrobiologie und Molekularbiologie, Giessen, Germany.
S K
SK
Hemschemeier
M
M
Kirndörfer
M
M
Hebermehl
G
G
Klug
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D009154:Mutation; D009876:Operon; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics*; D016354:Rhodobacter capsulatus / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D045322:Photosynthetic Reaction Center Complex Proteins; C072722:RegA protein, Bacteria