NapB in excess inhibits growth of Shewanella oneidensis by dissipating electrons of the quinol pool

Shewanella , a group of ubiquitous bacteria renowned for respiratory versatility, thrive in environments where various electron acceptors (EAs) of different chemical and physiological characteristics coexist. Despite being extensively studied, we still know surprisingly little about strategies by wh...

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Bibliographic Details
Published in:Scientific reports 2016-11, Vol.6 (1), p.37456, Article 37456
Main Authors: Jin, Miao, Zhang, Qianyun, Sun, Yijuan, Gao, Haichun
Format: Article
Language:English
Subjects:
38/44
38/70
631/326/1320
631/326/47/4112
Antimicrobial agents
Bacteria
Cyclic AMP
Cytochrome
Cytochrome c
E coli
Ecophysiology
Electron transport
Enzymes
Gene expression
Genetic engineering
Humanities and Social Sciences
Hydroquinone
multidisciplinary
Mutagenesis
Mutation
Nitrate reductase
Nitrates
Nitrites
Nitrogen dioxide
Physiology
Plasmids
Respiration
Science
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Summary:Shewanella , a group of ubiquitous bacteria renowned for respiratory versatility, thrive in environments where various electron acceptors (EAs) of different chemical and physiological characteristics coexist. Despite being extensively studied, we still know surprisingly little about strategies by which multiple EAs and their interaction define ecophysiology of these bacteria. Previously, we showed that nitrite inhibits growth of the genus representative Shewanella oneidensis on fumarate and presumably some other CymA (quinol dehydrogenase)-dependent EAs by reducing cAMP production, which in turn leads to lowered expression of nitrite and fumarate reductases. In this study, we demonstrated that inhibition of fumarate growth by nitrite is also attributable to overproduction of NapB, the cytochrome c subunit of nitrate reductase. Further investigations revealed that excessive NapB per se inhibits growth on all EAs tested, including oxygen. When overproduced, NapB acts as an electron shuttle to dissipate electrons of the quinol pool, likely to extracellullar EAs, because the Mtr system, the major electron transport pathway for extracellular electron transport, is implicated. The study not only sheds light on mechanisms by which certain EAs, especially toxic ones, impact the bacterial ecophysiology, but also provides new insights into how electron shuttle c -type cytochromes regulate multi-branched respiratory networks.
ISSN:2045-2322
2045-2322
DOI:10.1038/srep37456