The requirement of ArcA and Fnr for peak expression of the cyd operon in Escherichia coli under microaerobic conditions.
Transcriptional regulation of cyd, encoding the cytochrome d complex for O2 scavenging, was studied in Escherichia coli by monitoring phi(cyd-lac) expression under atmospheres containing 0-21% O2. Peak expression of this operon occurred under microaerobic conditions. Mutations in arcA (a trans-acting regulatory gene involved in aerobic respiration) greatly lowered phi(cyd-lac) expression under all conditions. Mutations in fnr (a trans-acting regulatory gene involved in anaerobic respiration) shifted the pattern of phi(cyd-lac) expression, lowering the microaerobic and aerobic expression. In an arcA-fnr double mutant, phi(cyd-lac) expression became insignificant, irrespective of the availability of O2. It thus appears that the expression of the phi(cyd-lac) operon is under dual control by the two pleiotropic activators, ArcA and Fnr, which interact to give the peak microaerobic expression.
Fu
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HA
Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115.
Iuchi
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Lin
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D000332:Aerobiosis; D017937:Cytochrome d Group; D003580:Cytochromes / Q000235:genetics* / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005809:Genes, Regulator; D009154:Mutation; D009876:Operon; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
D003580:Cytochromes; D017937:Cytochrome d Group; D001616:beta-Galactosidase