Antagonistic dark/light-induced SigB/SigD, group 2 sigma factors, expression through redox potential and their roles in cyanobacteria.
The expression of group 2 sigma factors is characterized in a cyanobacterium Synechocystis sp. PCC 6803 grown in culture, changing light conditions (white, red and blue light, and darkness), or the presence of drugs (rifampicin, chloramphenicol, DCMU, and DBMIB), and the roles of these sigma factors are elucidated. The expression of dark/light-induced SigB/SigD was accelerated under opposite redox (oxidation/reduction) states in an electron transport chain of photosynthesis. Expression of the dark-induced lrtA and light-induced psbA2/3 transcript was significantly reduced in the sigB and sigD knockout strains, respectively. Abundant amounts of sigB transcript and protein were observed in the sigC knockout strain, implying that SigC represses SigB expression under light. These findings clearly showed that SigB/SigD with another group 2 sigma, SigC, contribute to transcription for a subset of dark/light-responsive genes in the cyanobacterium. A possible model for SigB/SigD is presented and the potential ability for promoter recognition is also discussed.
Imamura
Sousuke
S
Laboratory of Molecular Genetics, College of Agriculture, Ibaraki University, Ami, Inashiki, Ibaraki 300-0393, Japan.
Asayama
Munehiko
M
Takahashi
Hiroyuki
H
Tanaka
Kan
K
Takahashi
Hideo
H
Shirai
Makoto
M
D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D002701:Chloramphenicol / Q000494:pharmacology; D000458:Cyanobacteria / Q000187:drug effects / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D012321:DNA-Directed RNA Polymerases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D003624:Darkness; D003991:Dibromothymoquinone / Q000494:pharmacology; D004237:Diuron / Q000494:pharmacology; D004579:Electron Transport / Q000502:physiology; D004926:Escherichia coli / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D008027:Light; D010788:Photosynthesis / Q000502:physiology; D012293:Rifampin / Q000494:pharmacology; D012808:Sigma Factor / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014158:Transcription, Genetic
D001426:Bacterial Proteins; C079011:SigB protein, Bacteria; D012808:Sigma Factor; D003991:Dibromothymoquinone; D002701:Chloramphenicol; D004237:Diuron; C081775:RNA polymerase sigma 70; D012321:DNA-Directed RNA Polymerases; D012293:Rifampin