Redox property and regulation of PpsR, a transcriptional repressor of photosystem gene expression in Rhodobacter sphaeroides.
PpsR from Rhodobacter sphaeroides is involved in the repression of photosystem gene expression. The PpsR protein was heterologously overexpressed and purified to homogeneity. Gel mobility shift assay showed that the purified PpsR has DNA-binding activity. SDS-PAGE analysis showed that some portions of PpsR were oxidized, indicating that intramolecular or intermolecular disulphide bonds were formed between the two cysteines in each subunit. When the disulphide bond of PpsR was reduced by DTT, the binding activity of PpsR to the puc promoter region distinctly increased. The changes in protein level and DNA-binding activity of PpsR were observed in a conjugant with an extra copy of the ppsR gene and in a PpsR-null mutant (PPS1), respectively. Both cysteines in PpsR existed in their reduced form under aerobic, anaerobic-dark and anaerobic-light growth conditions, as determined using thiol-specific chemical modification. In an AppA-null mutant (APP11), the binding activity and the amount of PpsR decreased compared to those of the wild-type and an appA-complemented strain, and decreased even more under anaerobic-dark conditions than under aerobic conditions. PpsR had a redox-sensitive property but retained its reduced state in the cell, and its amount was reduced by disruption of AppA.
Institute of Microbiology, Seoul National University, Seoul 151-742, Republic of Korea.
Seung-Hyun
SH
Cho
Laboratory of Biophysics, School of Biological Sciences, Seoul National University, Seoul 151-742, Republic of Korea.
Sang-Hee
SH
Youn
Center for Cell Signalling Research, Division of Molecular Life Sciences, Ewha Women's University, Seoul 120-750, Korea.
Seung-Rock
SR
Lee
Institute of Microbiology, Seoul National University, Seoul 151-742, Republic of Korea.
Hyung-Soon
HS
Yim
Institute of Microbiology, Seoul National University, Seoul 151-742, Republic of Korea.|Laboratory of Biophysics, School of Biological Sciences, Seoul National University, Seoul 151-742, Republic of Korea.
Sa-Ouk
SO
Kang
D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D003545:Cysteine / Q000737:chemistry; D004269:DNA, Bacterial / Q000235:genetics; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005420:Flavoproteins / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D015870:Gene Expression; D005798:Genes, Bacterial; D008954:Models, Biological; D010084:Oxidation-Reduction; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics* / Q000378:metabolism; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012242:Rhodobacter sphaeroides / Q000235:genetics* / Q000378:metabolism*
C116785:AppA protein, Rhodobacter sphaeroides; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D005420:Flavoproteins; D045322:Photosynthetic Reaction Center Complex Proteins; D012097:Repressor Proteins; D003545:Cysteine