Characterization and transcriptional regulation of the Synechocystis PCC 6803 petH gene, encodingferredoxin-NADP$^+$ oxidoreductase: involvement of a novel type ofdivergent operator

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• 作者：van Thor ; Jasper J. ; Hellingwerf ; Klaas J. ; Matthijs ; Hans C.P.
• 关键词：ferredoxin ; NADP+ oxidoreductase ; petH ; divergent operator ; antisense mRNA ; phosphoribulokinase ; prk Synechocystis PCC 6803 ; photosynthesis ; cyanobacteria
• 刊名：Plant Molecular Biology
• 出版年：1998
• 出版时间：1998
• 年：1998
• 卷：36
• 期：3
• 页码：353-363
• 全文大小：1.16 MB

文摘

The petH gene, encoding ferredoxin-NADP$^+$oxidoreductase (FNR), has been characterised in the unicellularcyanobacterium Synechocystis PCC 6803. Its product, FNR, was heterologouslyproduced and functionally characterized. The start-site of the monocystronicpetH transcript was mapped 523 bp upstream of the predicted PetH initiationcodon, resulting in an unusually large 5′-untranslated region.The 5′ end of the petH transcript is situated within the open readingframe of phosphoribulokinase (encoded by prk), which is transcribed inopposite orientation with respect to petH. The transcription start site ofthe prk transcript was mapped 219 bp upstream of the initiation codon,resulting in a 223 bp antisense region between both transcripts.

Under many conditions the expression of both genes (i.e. petH and prk) isco-regulated symmetrically at the transcriptional level, as was concludedfrom both northern hybridization experiments and from primer extensionanalyses; it became uncoupled, however, when specifically petH expressionwas stimulated, independent of prk expression, by stressing theSynechocystis cells with high salt concentrations. A model for a new type ofbidirectional operator, regulating the expression of petH and prk, isproposed.