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Regulation of succinate dehydrogenase (sdhCDAB) operon expression in Escherichia coli in response to carbon supply and anaerobiosis: role of ArcA and Fnr
Author(s) -
Park SoonJung,
Tseng ChingPing,
Gunsalus Robert P.
Publication year - 1995
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1995.tb02261.x
Subject(s) - biology , operon , escherichia coli , succinate dehydrogenase , lac operon , oxidative phosphorylation , biochemistry , gene expression , dehydrogenase , citric acid cycle , gene , enzyme , regulation of gene expression
Summary Succinate dehydrogenase (SDH) of Escherichia coli , the sole membrane‐bound enzyme of the tricarboxylic acid cycle, participates in the aerobic electron‐transport pathway to generate energy via oxidative phosphorylation reactions. Previous studies have established that succinate dehydrogenase (SDiH) synthesis is elevated by aerobiosis and supressed during growth with glucose. To examine how the sdhCDAB genes that encode SDH are regulated by changes in the environment, sdh–lacZ fusions were constructed and analysed in vivo following cell growth under a variety of alternative culture conditions. Expression of sdh–lacZ was highest under aerobic conditions and was decreased 10‐foid in the absence of oxygen. The fnr and arcA gene products are required for this oxygen control and each acts to repress sdhC–lacZ expression. Expression of sdh–lacZ also varied 10‐ to 14‐foid depending on the type of carbon substrate used or the medium richness. This control was shown to be independent of the crp and fruR gene products, and indicates that some other regulatory element exists in the ceil to adjust SDH enzyme levels accordingly. Iron and haem availability affected sdhC–lacZ expression by two‐ to threefold. Lastly, fold. Lastly, sdhC–lacZ expression was shown to vary with the cell growth rate during aerobic and anaerobic conditions.