title: Functional characterization of a mycothiol peroxidase in Corynebacterium glutamicum that uses both mycoredoxin and thioredoxin reducing systems in the response to oxidative stress.
abstract: Previous studies have identified a putative mycothiol peroxidase (MPx) in Corynebacterium glutamicum that shared high sequence similarity to sulfur-containing Gpx (glutathione peroxidase; CysGPx). In the present study, we investigated the MPx function by examining its potential peroxidase activity using different proton donors. The MPx degrades hydrogen peroxide and alkyl hydroperoxides in the presence of either the thioredoxin/Trx reductase (Trx/TrxR) or the mycoredoxin 1/mycothione reductase/mycothiol (Mrx1/Mtr/MSH) regeneration system. Mrx1 and Trx employ different mechanisms in reducing MPx. For the Mrx1 system, the catalytic cycle of MPx involves mycothiolation/demycothiolation on the Cys(36) sulfenic acid via the monothiol reaction mechanism. For the Trx system, the catalytic cycle of MPx involves formation of an intramolecular disulfide bond between Cys(36) and Cys(79) that is pivotal to the interaction with Trx. Both the Mrx1 pathway and the Trx pathway are operative in reducing MPx under stress conditions. Expression of mpx markedly enhanced the resistance to various peroxides and decreased protein carbonylation and intracellular reactive oxygen species (ROS) accumulation. The expression of mpx was directly activated by the stress-responsive extracytoplasmic function-σ (ECF-σ) factor [SigH]. Based on these findings, we propose that the C. glutamicum MPx represents a new type of GPx that uses both mycoredoxin and Trx systems for oxidative stress response.
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, PR China.
authors.forename: Meiru
authors.initials: M
authors.lastname: Si
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, PR China State Key Laboratory of Microbial Resources and Environmental Microbiology Research Center at Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, PR China.
authors.forename: Yixiang
authors.initials: Y
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, PR China.
authors.forename: Tietao
authors.initials: T
authors.lastname: Wang
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, PR China.
authors.forename: Mingxiu
authors.initials: M
authors.lastname: Long
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, PR China.
authors.forename: Wei
authors.initials: W
authors.lastname: Ding
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, PR China.
authors.forename: Can
authors.initials: C
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, PR China.
authors.forename: Xinmeng
authors.initials: X
authors.lastname: Guan
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, PR China.
authors.forename: Yingbao
authors.initials: Y
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, PR China.
authors.forename: Yao
authors.initials: Y
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, PR China xihuishen@nwsuaf.edu.cn.
authors.forename: Xihui
authors.initials: X
authors.lastname: Shen
authors.affiliation: State Key Laboratory of Microbial Resources and Environmental Microbiology Research Center at Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, PR China.
authors.forename: Shuang-Jiang
authors.initials: SJ
authors.lastname: Liu
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D048230:Corynebacterium glutamicum / Q000201:enzymology* / Q000235:genetics; D018384:Oxidative Stress / Q000502:physiology*; D010544:Peroxidases / Q000235:genetics / Q000378:metabolism*; D010545:Peroxides / Q000378:metabolism*; D013879:Thioredoxins / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D010545:Peroxides; D013879:Thioredoxins; D010544:Peroxidases
keywords: Corynebacterium glutamicum; SigH; mycothiol; mycothiol peroxidase; oxidative stress