Quantitative analysis of expression of two circadian clock-controlled gene clusters coding for the bidirectional hydrogenase in the cyanobacterium Synechococcus sp. PCC7942.
Hydrogen metabolism is of central interest in cyanobacterial research because of its potential applications. The gene expression and physiological role of the cyanobacterial bidirectional NAD(P)+-reducing hydrogenase are poorly understood. Transcription rates of hoxEF and hoxUYH encoding this enzyme have been studied in Synechococcus sp. PCC7942. PhoxU activity was about three times higher than that of PhoxE. Circadian phasing of both promoters was found to be synchronous and influenced expression levels by at least one order of magnitude. This is the first demonstration of circadian control of gene expression for any hydrogenase. For the majority of PhoxU-driven messages, transcription presumably terminates between hoxU and hoxH. Being part of a polycistronic hoxUYHW... operon, hoxW, encoding a protease involved in C-terminal processing of the hydrogenase large-subunit HoxH, is mainly expressed by its own promoter, PhoxW. The complex transcript formation may be a key feature for controlling bidirectional hydrogenase expression in vivo.
Schmitz
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Botanical Institute, The University of Cologne, Gyrhofstr. 15, D-50923 Köln, Germany. Oliver.Schmitz@uni-koeln.de
Boison
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Bothe
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D019677:Artificial Gene Fusion; D001426:Bacterial Proteins; D001483:Base Sequence; D002940:Circadian Rhythm / Q000235:genetics*; D000458:Cyanobacteria / Q000201:enzymology* / Q000235:genetics*; D017931:DNA Primers / Q000235:genetics; D010450:Endopeptidases / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D005798:Genes, Bacterial; D007763:Lac Operon; D008163:Luminescent Measurements; D005810:Multigene Family; D010088:Oxidoreductases / Q000235:genetics; D011401:Promoter Regions, Genetic
D001426:Bacterial Proteins; D017931:DNA Primers; D010088:Oxidoreductases; C021376:hydrogen dehydrogenase; D010450:Endopeptidases; C098852:HoxW protein, bacteria