期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 106, 期 44, 页码 18686-18691出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.0909464106
关键词
bactericidal; microbicidal
资金
- National Institutes of Health (NIH) [AI25606, HL075381, P30 DK017047, HL030086, HL086798]
- University of Washington
- DERC Mass Spectrometry Core
Reactive oxygen intermediates generated by neutrophils kill bacteria and are implicated in inflammatory tissue injury, but precise molecular targets are undefined. We demonstrate that neutrophils use myeloperoxidase (MPO) to convert methionine residues of ingested Escherichia coli to methionine sulfoxide in high yield. Neutrophils deficient in individual components of the MPO system (MPO, H2O2, chloride) exhibited impaired bactericidal activity and impaired capacity to oxidize methionine. HOCl, the principal physiologic product of the MPO system, is a highly efficient oxidant for methionine, and its microbicidal effects were found to correspond linearly with oxidation of methionine residues in bacterial cytosolic and inner membrane proteins. In contrast, outer envelope proteins were initially oxidized without associated microbicidal effect. Disruption of bacterial methionine sulfoxide repair systems rendered E. coli more susceptible to killing by HOCl, whereas over-expression of a repair enzyme, methionine sulfoxide reductase A, rendered them resistant, suggesting a direct role for methionine oxidation in bactericidal activity. Prominent among oxidized bacterial proteins were those engaged in synthesis and translocation of peptides to the cell envelope, an essential physiological function. Moreover, HOCl impaired protein translocation early in the course of bacterial killing. Together, our findings indicate that MPO-mediated methionine oxidation contributes to bacterial killing by neutrophils. The findings further suggest that protein translocation to the cell envelope is one important pathway targeted for damage.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据