| Mutation of NADH oxidase (nox) reveals an overlap of the oxygen- and acid-meditated stress responses in Streptococcus mutans. | |
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MedLine Citation:
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PMID: 22179247 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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NADH oxidase (Nox) is a flavin-containing enzyme used by Streptococcus mutans to reduce dissolved oxygen encountered during growth in the oral cavity. In this study, we have characterized the role of the NADH oxidase in the oxidative and acid stress responses of S. mutans. A nox-defective mutant strain of S. mutans and its parental strain, the genomic type strain UA159, were exposed to varying oxygen concentrations at pH values of 5 and 7 to better understand the adaptive mechanisms used by the organism to withstand environmental pressures. With the loss of nox, the activity of oxygen stress response enzymes such as superoxide dismutase and glutathione oxidoreductase were elevated, compared to controls, resulting in a greater adaptation to oxygen stress. In contrast, the loss of nox lead to a decreased ability to grow in a low pH environment despite an increased resistance to severe acid challenge. Analysis of the membrane fatty acid composition revealed that for both the nox mutant and UA159 parent strain, growth in an oxygen-rich environment resulted in high proportions of unsaturated membrane fatty acids, independent of external pH. The data indicate that S. mutans membrane fatty acid composition is responsive to oxidative stress, as well as changes in environmental pH values, as previously reported (E. M. Fozo and R. G. Quivey, Jr. Appl Environ Microbiol. 70:929-936, 2004). The heightened ability of the nox strain to survive acidic and oxidative environmental stress suggests a multi-faceted response system that is partially dependent on oxygen metabolites. |
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Authors:
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Adam M Derr; Roberta C Faustoferri; Matthew J Betzenhauser; Kaisha Gonzalez; Robert E Marquis; Robert G Quivey |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-12-16 |
Journal Detail:
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Title: Applied and environmental microbiology Volume: - ISSN: 1098-5336 ISO Abbreviation: - Publication Date: 2011 Dec |
Date Detail:
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Created Date: 2011-12-19 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 7605801 Medline TA: Appl Environ Microbiol Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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Center for Oral Biology. |
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