A phosphorylated DNA-binding protein is specific for the red-light signal during complementary chromatic adaptation in cyanobacteria.
Complementary chromatic adaptation is a mechanism by which some cyanobacteria that are able to synthesize phycoerythrin can adapt their pigment (phycobiliprotein) content to the incident wavelengths of the light. In Calothrix sp. PCC 7601 it concerns phycoerythrin (cpe operon), synthesized under green light, and phycocyanin-2 (cpc2 operon), expressed under red light, and involves transcriptional controls. With cell-free extracts from Calothrix sp. PCC 7601 grown under various light regimes, a protein designated RcaD was found by gel retardation experiments to specifically bind to the cpc2 promoter region and to be present only in red-light-grown cells. This protein was partially purified and its binding activity was shown to be sensitive to an alkaline phosphatase treatment. RcaD can protect two regions of the cpc2 promoter sequence against degradation by DNase I. Because its activity is detected only under the conditions required for cpc2 expression, we propose that RcaD is a positive effector of transcription.
Sobczyk
A
A
Physiologie Microbienne (CNRS URA 1129), Département de Biochimie et Génétique Moléculaire, Institut Pasteur, Paris, France.
Bely
A
A
Tandeau de Marsac
N
N
Houmard
J
J
D000222:Adaptation, Physiological / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D000458:Cyanobacteria / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects*; D004269:DNA, Bacterial / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D018506:Gene Expression Regulation, Plant; D005798:Genes, Bacterial; D017343:Genes, Plant; D008027:Light; D008969:Molecular Sequence Data; D009876:Operon; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D010798:Phycocyanin / Q000096:biosynthesis* / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011499:Protein Processing, Post-Translational; D017384:Sequence Deletion; D015398:Signal Transduction / Q000528:radiation effects; D013379:Substrate Specificity; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D010750:Phosphoproteins; D010940:Plant Proteins; D015534:Trans-Activators; D010798:Phycocyanin