Light-dependent regulation of photosynthesis genes in Rhodobacter sphaeroides 2.4.1 is coordinately controlled by photosynthetic electron transport via the PrrBA two-component system and the photoreceptor AppA.
Formation of the photosynthetic apparatus in Rhodobacter is regulated by oxygen tension and light intensity. Here we show that in anaerobically grown Rhodobacter cells a light-dependent increase in expression of the puc and puf operons encoding structural proteins of the photosynthetic complexes requires an active photosynthetic electron transport. The redox-sensitive CrtJ/PpsR repressor of photosynthesis genes, which was suggested to mediate electron transport-dependent signals, is not involved in this light-dependent signal chain. Our data reveal that the signal initiated in the photosynthetic reaction centre is transmitted via components of the electron transport chain and the PrrB/PrrA two-component system in Rhodobacter sphaeroides. Under blue light illumination in the absence of oxygen this signal leads to activation of photosynthesis genes and interferes with a blue-light repression mediated by the AppA photoreceptor and the PpsR transcriptional repressor in R. sphaeroides. Thus, light either sensed by a photoreceptor or initiating photosynthetic electron transport has opposite effects on the transcription of photosynthesis genes. Both signalling pathways involve redox-dependent steps that finally determine the effect of light on gene expression.
Happ
Hendrik N
HN
Institut für Mikrobiologie und Molekularbiologie, Universität Giessen, Heinrich-Buff-Ring 26-32, D-35392 Giessen, Germany.
Braatsch
Stephan
S
Broschek
Vera
V
Osterloh
Lisa
L
Klug
Gabriele
G
D000693:Anaerobiosis; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004579:Electron Transport / Q000502:physiology*; D005420:Flavoproteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D008027:Light; D009876:Operon; D010084:Oxidation-Reduction; D020283:Photoreceptors, Microbial / Q000235:genetics / Q000378:metabolism; D010788:Photosynthesis / Q000235:genetics / Q000502:physiology; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D012242:Rhodobacter sphaeroides / Q000235:genetics / Q000502:physiology*
C116785:AppA protein, Rhodobacter sphaeroides; D001426:Bacterial Proteins; D005420:Flavoproteins; D020283:Photoreceptors, Microbial; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D012097:Repressor Proteins