Biology subjects

Nandicoori, V.

Publications and source records attributed to Nandicoori, V..

6 recordsLinked to original sources

bioRxiv2025

PE11 promotes intracellular persistence of Mycobacterium tuberculosis by inhibiting autophagy and lysosomal biogenesis by targeting the FLCN-lactate-TFEB signaling axis

Mycobacterium tuberculosis (Mtb) employs multiple virulence factors, including cell wall-associated proteins, to evade host immune responses. PE11, a cell wall-localized esterase, contributes to Mtb persistence by facilitating cell wall remodelling and resistance to acidic and antibiotic stress. Herein we describe a novel role of PE11 in subverting host autophagy through disruption of TFEB-mediated lysosomal function. PE11 promotes FLCN-dependent depletion of intracellular lactate to destabilize TFEB and thereby downregulate genes essential for autophagic flux and lysosomal acidification. Using a PE11-deficient Mtb strain, we demonstrate that PE11 targets the FLCN-lactate axis to regulate TFEB stability. Exogenous lactate supplementation restored TFEB stability, enhanced lysosomal acidification, and significantly reduced intracellular bacterial burden. Lactate also synergized with frontline anti-tubercular drugs to improve Mtb clearance. These findings establish PE11 as a key immune evasion factor and highlight lactate as a promising host-directed therapeutic to enhance bacterial killing and reduce antibiotic-associated toxicity.

microbiology↗

bioRxiv2024

Wag31, a membrane tether, is crucial for lipid homeostasis in mycobacteria

The mycobacterial cytoskeletal protein Wag31 is necessary for maintaining cell shape and directing cellular growth and elongation. Wag31 has a characteristic N-terminal DivIVA-domain and a C-terminal coiled-coil domain. While the role of Wag31 in polar elongation is known, there is limited mechanistic insight on how it orchestrates growth and elongation. In this report, we delineate roles of the N- and C-terminal domains of Wag31 using genetics, state-of-the-art multi-omics, biochemical, and imaging approaches. We show that Wag31 predominantly interacts with several membrane-associated proteins involved in lipid metabolism, cell wall synthesis and division. Native levels of Wag31 are critical for the maintenance and distribution of membrane lipids. Both depletion and overexpression of Wag31 perturbs lipid homeostasis, leading to the formation of intracellular lipid inclusions (ILIs). Protein-lipid crosslinking and imaging studies reveal that purified Wag31 can bind and effectively tether Cardiolipin (CL)-containing liposomes. We further show that the tethering activity lies in the DivIVA-domain containing N-terminal of Wag31 while the C-terminal mediates protein-protein interactions of Wag31. Despite retaining its ability to interact with partner proteins, the DivIVA domain-deleted Wag31 mutant shows defects in liposome tethering in vitro and non-polar localization of CL in vivo, which eventually causes lethality. Our study suggests that membrane tethering licenses Wag31 to form scaffolds that help orchestrate protein-lipid and protein-protein interactions necessary for mycobacterial growth and survival.

microbiology↗

bioRxiv2024

A Mycobacterium tuberculosis secreted virulence factor disrupts host snRNP biogenesis

We earlier reported that Mycobacterium tuberculosis (Mtb) alters host RNA splicing to help its intracellular growth. Here, we report an unprecedented mechanism whereby a secreted virulence factor from Mtb interferes with the biogenesis of key spliceosomal components, causing an altered RNA splicing pattern. A high-throughput yeast-2-hybrid screen identified several Mtb-secreted proteins that can interact with the host RNA splicing factors (SFs). Through custom-designed in-cell assays, we show that one of those proteins, Rv1435c, targets specific exon-skipping events to alter RNA splicing. We show that Rv14345c or host splicing regulator 1 (hsr1) facilitates direct interaction between Mtb phagosomes and U5 snRNA and SNRPF, key components of the snRNPs. Genetic deletion of hsr1 reverses the specific exon-skipping events caused by WT Mtb infection. The{Delta} hsr1 strain shows compromised growth during ex vivo infection in the macrophages and in vivo infection in the mice. Tissue sections from the WT Mtb or{Delta} hsr1-infected mice showed significant hsr1-dependent SNRPF staining, a phenomenon also noted in the human intestinal tuberculosis (ITB) biopsies. We infer that hsr1 is a virulence factor which alters RNA splicing by interacting with U5snRNA and SNRPF. The splicing regulators from the host and pathogen are novel targets for anti-tuberculosis therapy.

molecular biology↗

bioRxiv2023

A mitochondrial quality control mechanism reverses the phagosome maturation arrest caused by Mycobacterium tuberculosis

Phagosome maturation arrest (PMA) imposed by Mycobacterium tuberculosis (Mtb) is a classic tool that helps Mtb evade macrophage anti-bacterial responses. The exclusion of RAB7, a small GTPase, from Mtb-phagosomes causes PMA. Here, we report an unexpected mechanism that triggers crosstalk between the mitochondrial quality control (MQC) and the phagosome maturation pathways that reverses the PMA. CRISPR-mediated p62/SQSTM1 depletion (p62KD) does not appear to impact mitochondrial quality. The p62KD cells are restrictive to Mtb growth, triggered by an increasingly oxidative environment and increased lysosomal targeting. The lysosomal targeting of Mtb is facilitated by enhanced TOM20+ mitochondria-derived vesicles (MDVs) biogenesis, a key MQC mechanism. In p62KD cells, TOM20+-MDVs biogenesis is MIRO1/MIRO2-dependent and gets delivered to lysosomes for degradation in a RAB7-dependent manner. Upon infection in p62KD cells, TOM20+-MDVs get extensively targeted to Mtb-phagosomes, inadvertently facilitating RAB7 recruitment, PMA reversal and lysosomal targeting of Mtb; the phenotype also replicated in p62/SQSTM1 knockout cells. Triggering MQC collapse in p62KDcells further diminishes Mtb survival, signifying cooperation between redox- and lysosome-mediated mechanisms. The MQC-anti-bacterial pathway crosstalk could be exploited for host-directed anti-tuberculosis therapies.

microbiology↗

bioRxiv2023

Neutrophil-derived IL-17 limits protective host responses and promotes tuberculosis pathogenesis

The protective correlates of Mycobacterium tuberculosis (Mtb) infection-elicited host immune responses are incompletely understood. Here, we report pro-pathogenic crosstalk involving Ly6G+granulocytes (Ly6G+Gra), IL-17 and COX2. We show that in the lungs of Mtb-infected wildtype mice, either BCG-vaccinated or not, most intracellular bacilli are Ly6G+Gra-resident four weeks post-infection onwards. In the genetically susceptible IFN{psi} -/- mice, excessive Ly6G+Gra infiltration correlates with severe bacteraemia. Neutralizing IL-17 (anti-IL17mAb) and COX2 inhibition by celecoxib reverse Ly6G+Gra infiltration, associated pathology and death in IFN{psi} -/- mice. Surprisingly, Ly6G+Gra also serves as the major source of IL-17 in the lungs of Mtb-infected WT or IFN{psi} -/- mice. The IL-17-COX2-Ly6G+Gra interplay also operates in WT mice. Inhibiting ROR{psi}t, the key transcription factor for IL-17 production or COX2, reduces the bacterial burden in Ly6G+Gra, leading to reduced bacterial burden and pathology in the lungs of WT mice. In the Mtb-infected WT mice, COX2 inhibition abrogates IL-17 levels in the lung homogenates and significantly enhances BCGs protective efficacy, mainly by targeting the Ly6G+Gra-resident Mtb pool, a phenotype also observed when IL-17 is blocked by ROR{psi}t inhibitor. Furthermore, in pulmonary TB patients, high neutrophil count and IL-17 correlated with adverse treatment outcomes. Together, our results suggest that IL-17 and PGE2 are the negative correlates of protection, and we propose targeting the pro-pathogenic IL-17-COX2-Ly6G+Gra axis for TB prevention and therapy.

immunology↗

bioRxiv2017

Mycobacterium tuberculosis LprE enhances bacterial persistence by inhibiting cathelicidin and autophagy in macrophages

Mycobacterium tuberculosis(Mtb) lipoproteins are known to facilitate bacterial survival by manipulating the host immune responses. Here, we have characterized a novel Mtb lipoprotein LprE(LprEMtb), and demonstrated its role in mycobacterial survival. LprEMtb acts by down-regulating the expression of cathelicidin, Cyp27B1, VDR and p38-MAPK via TLR-2 signaling pathway. Deletion of lprEMtb resulted in induction of cathelicidin and decreased survival in the host. Interestingly, LprEMtb was also found to inhibit autophagy mechanism to dampen host immune response. Episomal expression of LprEMtb in non-pathogenic Mycobacterium smegmatis(Msm) increased bacillary persistence by down-regulating the expression of cathelicidin and autophagy, while deletion of LprEMtb orthologue in Msm, had no effect on cathelicidin and autophagy expression. Moreover, LprEMtb blocked phago-lysosome fusion by suppressing the expression of EEA1, Rab7 and LAMP-1 endosomal markers by down-regulating IL-12 and IL-22 cytokines. Our results indicate that LprEMtb plays an important role in mycobacterial pathogenesis in the context of innate immunity.

physiology↗