Mycobacterium tuberculosis DosR Regulon Gene Rv0079 Encodes a Putative, ‘Dormancy Associated Translation Inhibitor (DATIN)’ Ashutosh Kumar 1 , Mohammad Majid 1 , Ralph Kunisch 2 , Pittu Sandhya Rani 1 , Insaf A. Qureshi 3 , Astrid Lewin 2 , Seyed E. Hasnain 4,5,6 , Niyaz Ahmed 1,7 * 1 Pathogen Biology Laboratory, Department of Biotechnology, School of Life Sciences, University of Hyderabad, Hyderabad, India, 2 Robert Koch Institute, Berlin, Germany, 3 Department of Biotechnology, School of Life Sciences, University of Hyderabad, Hyderabad, India, 4 School of Biological Sciences, Indian Institute of Technology, New Delhi, India, 5 Institute of Life Sciences, University of Hyderabad Campus, Hyderabad, India, 6 King Saud University, Riyadh, Saudi Arabia, 7 Institute of Biological Sciences, University of Malaya, Kuala Lumpur, Malaysia Abstract Mycobacterium tuberculosis is a major human pathogen that has evolved survival mechanisms to persist in an immune- competent host under a dormant condition. The regulation of M. tuberculosis metabolism during latent infection is not clearly known. The dormancy survival regulon (DosR regulon) is chiefly responsible for encoding dormancy related functions of M. tuberculosis. We describe functional characterization of an important gene of DosR regulon, Rv0079, which appears to be involved in the regulation of translation through the interaction of its product with bacterial ribosomal subunits. The protein encoded by Rv0079, possibly, has an inhibitory role with respect to protein synthesis, as revealed by our experiments. We performed computational modelling and docking simulation studies involving the protein encoded by Rv0079 followed by in vitro translation and growth curve analysis experiments, involving recombinant E. coli and Bacille Calmette Gue ´rin (BCG) strains that overexpressed Rv0079. Our observations concerning the interaction of the protein with the ribosomes are supportive of its role in regulation/inhibition of translation. We propose that the protein encoded by locus Rv0079 is a ‘dormancy associated translation inhibitor’ or DATIN. Citation: Kumar A, Majid M, Kunisch R, Rani PS, Qureshi IA, et al. (2012) Mycobacterium tuberculosis DosR Regulon Gene Rv0079 Encodes a Putative, ‘Dormancy Associated Translation Inhibitor (DATIN)’. PLoS ONE 7(6): e38709. doi:10.1371/journal.pone.0038709 Editor: Javed N. Agrewala, Institute of Microbial Technology, India Received February 7, 2012; Accepted May 11, 2012; Published June 13, 2012 Copyright: ß 2012 Kumar et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This work was primarily supported by a Centre of Excellence Grant from the Department of Biotechnology of the Indian Government entitled ‘Multidisciplinary approaches aimed at interventions against Mycobacterium tuberculosis’ [BT/01/C0E/07/02] to NA (component B2b). The authors would like to also acknowledge support from the German Research Foundation (DFG) sponsored international research training group (IRTG) entitled ‘Internationales Graduiertenkolleg - functional molecular infection epidemiology - GRK1673 (Berlin-Hyderabad)’ of which NA is a speaker, and partial support through the University of Malaya High Impact Research (HIR) grant (Ref. UM.C/625/1HIR/MOHE/CHAN-02). SEH is a J. C. Bose National Fellow (India) and a Robert Koch Fellow of the Robert Koch Institute, Berlin. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have read the journal’s policy and have the following conflicts: Niyaz Ahmed is a Section Editor of PLoS ONE. This does not alter the authors’ adherence to all the PLoS ONE policies on sharing data and materials. * E-mail: ahmed.nizi@gmail.com Introduction Tuberculosis (TB) is a chronic infectious disease caused by Mycobacterium tuberculosis which is linked to high morbidity and mortality worldwide. M. tuberculosis can exist in active form or can remain alive in a dormant state in lungs after forming granuloma where it can prolong its persistence without replication [1]. The tubercle bacilli in the dormant or latent state may not be affected by antibiotics or the host immune system due to their bare minimum growth [2,3]. Several studies have indicated that, under latency, the granuloma offers a niche with increased concentration of nitric oxide, low oxygen and absence of nutrients. To survive under such unfavourable conditions [2–6], M. tuberculosis might have evolved mechanism(s) whereby it decreases the rate of protein synthesis to conserve its cellular resources. Such mechanisms have not been clearly deciphered. M. tuberculosis genome encodes a regulon of 48 constituent genes called the dormancy survival regulon (DosR regulon) [6]. In- hibition of aerobic respiration causes up-regulation of the transcription factor, DosR, pointing out that the control of the regulon is related to physiology of respiration in M. tuberculosis [6]. Although many of the constituent genes of DosR regulon encode hypothetical proteins, growing knowledge of the conditions under which these genes are likely up-regulated could lead to their role in adaptation of M. tuberculosis to the host environment [6]. The humoral immune response for DosR regulon encoded antigens is stronger in latently infected individuals when compared to individuals with active infection [7] suggesting that DosR regulon genes are more likely expressed during latency. Many proteins encoded by the genes of this regulon are thought to be helpful to obtain energy from alternative sources of carbon such as glyoxylate metabolism, nitrate reduction and fatty acid metabolism [6,8]. Several of the members of DosR regulon which might be significant in understanding dormancy regulation could not be functionally characterized as yet. Rv0079 is the first member, by order [6], in the DosR regulon that has not been functionally characterized, although it has been computationally shown to encode a predicted translation factor [9]. PLoS ONE | www.plosone.org 1 June 2012 | Volume 7 | Issue 6 | e38709