A Mycobacterial Phosphoribosyltransferase Promotes Bacillary Survival by Inhibiting Oxidative Stress and Autophagy Pathways in Macrophages and Zebrafish

Mohanty, Soumitra and Jagannathan, Lakshmanan and Ganguli, Geetanjali and Padhi, Avinash and Roy, Debasish and Alaridah, Nader and Saha, Pratip and Nongthomba, Upendra and Godaly, Gabriela and Gopal, Ramesh Kumar and Banerjee, Sulagna and Sonawane, Avinash (2015) A Mycobacterial Phosphoribosyltransferase Promotes Bacillary Survival by Inhibiting Oxidative Stress and Autophagy Pathways in Macrophages and Zebrafish. In: JOURNAL OF BIOLOGICAL CHEMISTRY, 290 (21). pp. 13321-13343.

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Abstract

Mycobacterium tuberculosis employs various strategies to modulate host immune responses to facilitate its persistence in macrophages. The M. tuberculosis cell wall contains numerous glycoproteins with unknown roles in pathogenesis. Here, by using Concanavalin A and LC-MS analysis, we identified a novel mannosylated glycoprotein phosphoribosyltransferase, encoded by Rv3242c from M. tuberculosis cell walls. Homology modeling, bioinformatic analyses, and an assay of phosphoribosyltransferase activity in Mycobacterium smegmatis expressing recombinant Rv3242c (MsmRv3242c) confirmed the mass spectrometry data. Using Mycobacterium marinum-zebrafish and the surrogate MsmRv3242c infection models, we proved that phosphoribosyltransferase is involved in mycobacterial virulence. Histological and infection assays showed that the M. marinum mimG mutant, an Rv3242c orthologue in a pathogenic M. marinum strain, was strongly attenuated in adult zebrafish and also survived less in macrophages. In contrast, infection with wild type and the complemented Delta mimG: Rv3242c M. marinum strains showed prominent pathological features, such as severe emaciation, skin lesions, hemorrhaging, and more zebrafish death. Similarly, recombinant Msm Rv3242c bacteria showed increased invasion in non-phagocytic epithelial cells and longer intracellular survival in macrophages as compared with wild type and vector control M. smegmatis strains. Further mechanistic studies revealed that the Rv3242c- and mimG-mediated enhancement of intramacrophagic survival was due to inhibition of autophagy, reactive oxygen species, and reduced activities of superoxide dismutase and catalase enzymes. Infection with MsmRv3242c also activated the MAPK pathway, NF-kappa B, and inflammatory cytokines. In summary, we show that a novel mycobacterial mannosylated phosphoribosyltransferase acts as a virulence and immunomodulatory factor, suggesting that it may constitute a novel target for antimycobacterial drugs.

Item Type:	Journal Article
Publication:	JOURNAL OF BIOLOGICAL CHEMISTRY
Publisher:	AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
Additional Information:	Copy right for this article belongs to the AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC, 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3996 USA
Department/Centre:	Division of Biological Sciences > Molecular Reproduction, Development & Genetics
Date Deposited:	26 Jun 2015 05:39
Last Modified:	26 Jun 2015 05:39
URI:	http://eprints.iisc.ac.in/id/eprint/51766

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