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Virulence Factor SenX3 Is the Oxygen-Controlled Replication Switch ofMycobacterium tuberculosis

DIR@IMTECH: CSIR-Institute of Microbial Technology

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Title Virulence Factor SenX3 Is the Oxygen-Controlled Replication Switch ofMycobacterium tuberculosis
 
Creator Singh, Nisha
Kumar, Ashwani
 
Subject QR Microbiology
 
Description Aim: Morphogenetic switching between the replicating and nonreplicating states of Mycobacterium tuberculosis is regulated by oxygen, nitric oxide, and carbon monoxide levels. The mechanisms by which M. tuberculosis senses these diatomic gases remain poorly understood. In this study, we have examined whether virulence factor SenX3 plays any role in oxygen sensing. Results: In this study, we demonstrate that the virulence factor SenX3 is a heme protein that acts as a three-way sensor with three levels of activity. The oxidation of SenX3 heme by oxygen leads to the activation of its kinase activity, whereas the deoxy-ferrous state confers a moderate kinase activity. The binding of nitric oxide and carbon monoxide inhibits kinase activity. Consistent with these biochemical properties, the SenX3 mutant of M. tuberculosis is capable of attaining a nonreplicating persistent state in response to hypoxic stress, but its regrowth on the restoration of ambient oxygen levels is significantly attenuated compared with the wild-type and the complemented mutant strains. Furthermore, the presence of signaling concentrations of nitric oxide and carbon monoxide was able to inhibit the regrowth of M. tuberculosis in response to ambient oxygen levels. Innovation and Conclusions: Evidence presented in this study delineates a plausible mechanism explaining the oxygen-induced reactivation of tuberculosis diseases in humans after many years of latent infection. Furthermore, this study implicates nitric oxide and carbon monoxide in the inhibition of mycobacterial growth from the nonreplicating state. Antioxid. Redox Signal. 22, 603–613.
 
Publisher Mary Ann Liebert, Inc
 
Date 2015
 
Type Article
PeerReviewed
 
Relation http://dx.doi.org/10.1089/ars.2014.6020
http://crdd.osdd.net/open/1821/
 
Identifier Singh, Nisha and Kumar, Ashwani (2015) Virulence Factor SenX3 Is the Oxygen-Controlled Replication Switch ofMycobacterium tuberculosis. Antioxidants & Redox Signaling, 22 (7). pp. 603-613. ISSN 1523-0864