title: Reduced expression of cytochrome oxidases largely explains cAMP inhibition of aerobic growth in Shewanella oneidensis.
abstract: Inhibition of bacterial growth under aerobic conditions by elevated levels of cyclic adenosine 3',5'-monophosphate (cAMP), first revealed more than 50 years ago, was attributed to accumulation of toxic methylglyoxal (MG). Here, we report a Crp-dependent mechanism rather than MG accumulation that accounts for the phenotype in Shewanella oneidensis, an emerging research model for the bacterial physiology. We show that a similar phenotype can be obtained by removing CpdA, a cAMP phosphodiesterase that appears more effective than its Escherichia coli counterpart. Although production of heme c and cytochromes c is correlated well with cAMP levels, neither is sufficient for the retarded growth. Quantities of overall cytochromes c increased substantially in the presence of elevated cAMP, a phenomenon resembling cells respiring on non-oxygen electron acceptors. In contrast, transcription of Crp-dependent genes encoding both cytochromes bd and cbb3 oxidases is substantially repressed under the same condition. Overall, our results suggest that cAMP of elevated levels drives cells into a low-energetic status, under which aerobic respiration is inhibited.
authors.affiliation: Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Yin
authors.affiliation: Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
authors.forename: Qiu
authors.initials: Q
authors.lastname: Meng
authors.affiliation: Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
authors.forename: Huihui
authors.initials: H
authors.lastname: Fu
authors.affiliation: Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China.|Key Laboratory for Agro-Microbial Research and Utilization, Zhejiang Province Hangzhou, Zhejiang, 310058, China.
authors.forename: Haichun
authors.initials: H
authors.lastname: Gao
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism; D000332:Aerobiosis; D000242:Cyclic AMP / Q000494:pharmacology*; D002373:Cyclic AMP Receptor Protein / Q000378:metabolism*; D003576:Electron Transport Complex IV / Q000096:biosynthesis*; D004734:Energy Metabolism; D015870:Gene Expression / Q000187:drug effects*; D006131:Growth Inhibitors / Q000494:pharmacology*; D020592:Shewanella / Q000187:drug effects* / Q000254:growth & development* / Q000378:metabolism
chemical_list: D002373:Cyclic AMP Receptor Protein; D006131:Growth Inhibitors; D000242:Cyclic AMP; D003576:Electron Transport Complex IV; D015105:3',5'-Cyclic-AMP Phosphodiesterases