title: Combined effect of loss of the caa3 oxidase and Crp regulation drives Shewanella to thrive in redox-stratified environments.
abstract: Shewanella species are a group of facultative Gram-negative microorganisms with remarkable respiration abilities that allow the use of a diverse array of terminal electron acceptors (EA). Like most bacteria, S. oneidensis possesses multiple terminal oxidases, including two heme-copper oxidases (caa3- and cbb3-type) and a bd-type quinol oxidase. As aerobic respiration is energetically favored, mechanisms underlying the fact that these microorganisms thrive in redox-stratified environments remain vastly unexplored. In this work, we discovered that the cbb3-type oxidase is the predominant system for respiration of oxygen (O2), especially when O2 is abundant. Under microaerobic conditions, the bd-type quinol oxidase has a significant role in addition to the cbb3-type oxidase. In contrast, multiple lines of evidence suggest that under test conditions the caa3-type oxidase, an analog to the mitochondrial enzyme, has no physiological significance, likely because of its extremely low expression. In addition, expression of both cbb3- and bd-type oxidases is under direct control of Crp (cAMP receptor protein) but not the well-established redox regulator Fnr (fumarate nitrate regulator) of canonical systems typified in Escherichia coli. These data, collectively, suggest that adaptation of S. oneidensis to redox-stratified environments is likely due to functional loss of the caa3-type oxidase and switch of the regulatory system for respiration.
authors.affiliation: Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China.
authors.forename: Guangqi
authors.initials: G
authors.lastname: Zhou
authors.forename: Jianhua
authors.initials: J
authors.lastname: Yin
authors.forename: Haijiang
authors.initials: H
authors.lastname: Chen
authors.forename: Yijie
authors.initials: Y
authors.lastname: Hua
authors.forename: Linlin
authors.initials: L
authors.lastname: Sun
authors.forename: Haichun
authors.initials: H
authors.lastname: Gao
mesh_terms: D000332:Aerobiosis / Q000235:genetics; D001483:Base Sequence; D002373:Cyclic AMP Receptor Protein / Q000378:metabolism*; D003580:Cytochromes / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000235:genetics / Q000378:metabolism; D004783:Environmental Microbiology; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000235:genetics* / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D020592:Shewanella / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism
chemical_list: D002373:Cyclic AMP Receptor Protein; D003580:Cytochromes; D010088:Oxidoreductases; C414443:cbb3 oxidase; D003576:Electron Transport Complex IV; D010100:Oxygen