bims-nocaut 2025-07-20 papers

Issue of 2025–07–20
three papers selected by
Quentin Frenger, University of Strasbourg

Int Rev Immunol. 2025 Jul 18. 1-27

Phagosomal escape and sabotage: The role of ESX-1 and PDIMs in Mycobacterium tuberculosis pathogenesis.

Mohd Shariq, Farhan Ahmed, Onaiza Ansari, Anam Mursaleen, Javaid Ahmad Sheikh.

Mycobacterium tuberculosis (M. tb) employs diverse virulence factors to evade immune defenses and persist intracellularly. The ESAT-6 secretion system-1 (ESX-1) type VII secretion system (T7SS) releases EsxA, EspA, and EspB, inducing phagosomal rupture and cytosolic access while triggering host defenses, including galectin recruitment and stress granule formation. To counteract host responses, M. tb utilizes phthiocerol dimycocerosates (PDIMs) to inhibit autophagy and LC3-associated phagocytosis (LAP) by suppressing NADPH oxidase (NOX2) recruitment and reactive oxygen species (ROS) production. Additionally, CspA blocks LC3 lipidation, impairing LAP activation and phagosome maturation. EsxG and EsxH interfere with ESCRT-mediated phagosomal repair, further enhancing intracellular survival. Cytosolic M. tb is ubiquitinated by host E3 ligases, marking it for selective autophagy (xenophagy), yet M. tb evades degradation by manipulating autophagic flux. Simultaneously, M. tb-derived DNA activates the cyclic GMP-AMP synthase-stimulator of interferon response cGAMP interactor 1 (CGAS-STING1) axis, leading to type I interferon (IFN) signaling and inflammasome activation, which drive IL-1B and IL-18 secretion, necrosis, and pyroptosis, facilitating bacterial dissemination. Additionally, exosomes released during infection disseminate bacterial components, modulating immune responses systemically. This review uniquely integrates current findings on the coordinated actions of ESX-1 T7SS and PDIMs in mediating phagosomal rupture and immune evasion, offering a unified framework for understanding M. tb's intracellular survival strategies. By bridging lipid- and protein-mediated virulence mechanisms and their impact on host autophagy, inflammasome activation, and phagosomal repair pathways, this work provides novel insights into therapeutic targets aimed at restoring host immune function.

Keywords: Autophagy; ESX-1; EsxA; PDIM; cytosol access; inflammasome; lysosome

DOI: https://doi.org/10.1080/08830185.2025.2531828

Nat Struct Mol Biol. 2025 Jul 11.

A heterotrimeric protein complex assembles the metazoan V-ATPase upon dissipation of proton gradients.

Christopher Nardone, Julian Mintseris, Dingwei He, Justine C Rutter, Benjamin L Ebert, Steven P Gygi, Tom Rapoport.

Organelles such as lysosomes and synaptic vesicles are acidified by V-ATPases, which consist of a cytosolically oriented V1 complex that hydrolyzes ATP and a membrane-embedded VO complex that pumps protons. In yeast, V1-VO association is facilitated by the RAVE (regulator of H+-ATPase of the vacuolar and endosomal membrane) complex, but how higher eukaryotes assemble V-ATPases remains unclear. Here we identify a metazoan RAVE complex (mRAVE) whose structure and composition are notably divergent from the ancestral counterpart. mRAVE consists of DMXL1 or DMXL2, WDR7 and the central linker ROGDI. DMXL1 and DMXL2 interact with subunits A and D of the inactive, isolated V1. On dissipation of proton gradients, mRAVE binds to V1 and VO, forming a supercomplex on the membrane. mRAVE then catalyzes V1-VO assembly, enabling lysosomal acidification, neurotransmitter loading into vesicles and ATG16L1 recruitment for LC3/ATG8 conjugation onto single membranes. Our findings provide a molecular basis for neurological disorders caused by mRAVE mutations.

DOI: https://doi.org/10.1038/s41594-025-01610-9

PLoS Biol. 2025 Jul 16. 23(7): e3002958

Influenza A virus induces PI4P production at the endoplasmic reticulum in an ATG16L1-dependent manner to promote the egress of viral ribonucleoproteins.

Carla Alemany, Juliane Da Graça, Quentin Giai Gianetto, Maud Dupont, Sylvain Paisant, Thibaut Douché, Catherine Isel, Cédric Delevoye, Lydia Danglot, Mariette Matondo, Etienne Morel, Jean-Baptiste Brault, Nadia Naffakh.

The genomic RNAs of influenza A viruses (IAVs) are replicated in the nucleus of infected cells in the form of viral ribonucleoproteins (vRNPs) before being exported to the cytoplasm. The small GTPase RAB11A is involved in the transport of vRNPs to the sites of viral assembly at the plasma membrane, but the molecular mechanisms involved remain largely unknown. Here we show that IAV infection remodels the architecture of the endoplasmic reticulum (ER) sheets, where vRNPs tend to accumulate in the absence of RAB11A. To decipher the interplay between RAB11A, vRNPs, and the ER, we investigated viral-induced perturbations of RAB11A proximity interactome. To this end, we generated cells stably expressing a TurboID-RAB11A fusion protein and performed biotin-based proximity labeling upon viral infection. We found that cellular regulators of phophatidylinositol-4-phosphate (PI4P) homeostasis, including the autophagic and stress response protein ATG16L1, are significantly enriched at the vicinity of RAB11A in infected cells. Infection induces an increase in cellular PI4P levels in an ATG16L1-dependent manner, while ATG16L1 relocalizes to ER membranes upon infection. Depletion of ATG16L1 decreases the co-distribution of vRNPs with PI4P punctae on ER membranes, and reduces the accumulation of vRNPs at the plasma membrane as well as the production of IAV infectious particles. Our data extend to IAVs the notion that viruses can modulate the metabolism and localization of phosphoinositides to control host membrane dynamics and point to the ER as an essential platform for vRNP transport. They provide evidence for a pivotal role of ATG16L1 in regulating the identity of endomembranes and coordinating RAB11A and PI4P-enriched membranes to ensure delivery of vRNPs to the plasma membrane.

DOI: https://doi.org/10.1371/journal.pbio.3002958