S- nitrosylation- triggered secretion of mycobacterial PknG leads to phosphorylation of SODD to prevent apoptosis of infected macrophages

• 成果类型: Article
• 署名作者: Saha, Saradindu; Roy, Sadhana; Hazra, Arnab; Das, Debayan; Kumar, Vimal; Singh, Amit Kumar; Singh, Ajay Vir; Mondal, Rajesh; Dasgupta, Somdeb Bose
• 署名单位: Indian Institute of Technology System (IIT System); Indian Institute of Technology (IIT) - Kharagpur; Indian Council of Medical Research (ICMR); ICMR - National JALMA Institute for Leprosy & Other Mycobacterial Diseases, Agra; Indian Council of Medical Research (ICMR); Indian Council of Medical Research (ICMR); ICMR - National Institute for Research in Tuberculosis (NIRT); Indian Council of Medical Research (ICMR); ICMR - National Institute for Research in Environmental Health (NIREH)
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-9461
• DOI: 10.1073/pnas.2404106122
• 发表日期: 2025-03-11
• 关键词: pathogenic mycobacteria; tuberculosis; death; survival; immunity

摘要

The tuberculosis-causing agent Mycobacterium tuberculosis (M.tb) establishes its niche inside macrophages by secretion of several virulence factors and engaging many host factors. Mycobacterial infection of macrophages results in a proinflammatory trigger-mediated secretion of TNFc. Protein kinase G (PknG), a Serine/Threonine kinase, is essential for mycobacterial survival within the macrophage. Pathogenic mycobacteria, upon infection, can trigger the secretion of proinflammatory cytokine TNFc, but whether secreted PknG plays any role in TNFc secretion at early stages of infection remains undeciphered. Moreover, at early infection stages, prevention of macrophage apoptosis is vital to successful mycobacterial pathogenesis. Our studies show that mycobacteria-secreted PknG can dampen the expression and concomitant secretion of proinflammatory TNFc. During early infection, M.tb infection-induced generation of reactive nitrogen intermediates (RNI) leads to S-nitrosylation of PknG on Cys109, thereby enabling its secretion into macrophages. Upon M.tb infection, secreted S-nitrosylated PknG phosphorylates macrophage Silencer of Death Domains (SODD) at Thr405, as identified through our phosphoproteomic studies. Thereafter, phosphorylated SODD, through an irreversible binding with the TNFR1 death domain, prevents Caspase8 activation and concomitant extrinsic apoptotic trigger. Moreover, alveolar macrophages from mice infected with PknG-knockout M.tb also exhibited SODD phosphorylation and hindered Caspase8 activation to prevent extrinsic macrophage apoptosis. Therefore, this work exhibits S-nitrosylation-mediated secretion of PknG to induce phosphorylation of macrophage SODD, which, through irreversible interaction with TNFR1, prevented extrinsic macrophage apoptosis at the early stages of infection.