A deficiency in cyclic AMP results in pH-sensitive growth of Escherichia coli K-12.
Mutants of Escherichia coli K-12 deficient in adenyl cyclase (cya) and catabolite activator protein (crp) have been shown to grow more slowly than their parent strains in glucose-minimal medium. Their growth rate decreased markedly with increasing pH between 6 and 7.8. We have shown that this pH sensitivity is a direct consequence of the cya mutation, because a mutation to pH resistance also restored ability to ferment a variety of sugars. The proton motive force-dependent uptake of proline and glutamate was also reduced and sensitive to pH in the cya mutant. The membrane-bound ATPase activity was normal. The rate of oxygen uptake by cells, although reduced, was pH insensitive. We suggest several explanations for this phenotype, including a possible defect in energy transduction.
Ahmad
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Department of Biological Sciences, Concordia University, Montreal, Quebec, Canada.
Newman
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EB
D000262:Adenylyl Cyclases / Q000235:genetics; D000596:Amino Acids / Q000378:metabolism; D003470:Culture Media; D000242:Cyclic AMP / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D005971:Glutamates / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D009154:Mutation; D010100:Oxygen / Q000378:metabolism; D010641:Phenotype; D011392:Proline / Q000378:metabolism
D000596:Amino Acids; D003470:Culture Media; D005971:Glutamates; D011392:Proline; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; D010100:Oxygen