期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2017
卷号：114
期号：23
页码：6022-6027
DOI：10.1073/pnas.1703576114
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Endogenous hydrogen sulfide (H2S) renders bacteria highly resistant to oxidative stress, but its mechanism remains poorly understood. Here, we report that 3-mercaptopyruvate sulfurtransferase (3MST) is the major source of endogenous H2S in Escherichia coli . Cellular resistance to H2O2 strongly depends on the activity of mstA , a gene that encodes 3MST. Deletion of the ferric uptake regulator (Fur) renders ∆ mstA cells hypersensitive to H2O2. Conversely, induction of chromosomal mstA from a strong pLtetO-1 promoter (P tet - mstA ) renders ∆ fur cells fully resistant to H2O2. Furthermore, the endogenous level of H2S is reduced in ∆ fur or ∆ sodA ∆ sodB cells but restored after the addition of an iron chelator dipyridyl. Using a highly sensitive reporter of the global response to DNA damage (SOS) and the TUNEL assay, we show that 3MST-derived H2S protects chromosomal DNA from oxidative damage. We also show that the induction of the CysB regulon in response to oxidative stress depends on 3MST, whereas the CysB-regulated l -cystine transporter, TcyP, plays the principle role in the 3MST-mediated generation of H2S. These findings led us to propose a model to explain the interplay between l -cysteine metabolism, H2S production, and oxidative stress, in which 3MST protects E. coli against oxidative stress via l -cysteine utilization and H2S-mediated sequestration of free iron necessary for the genotoxic Fenton reaction.
