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Membrane-associated effluxosomes coordinate multi-metal resistance in Mycobacterium tuberculosis - The EMBO Journal

Bacterial pathogens must withstand metal-induced stress during infection, yet the mechanisms by which they sense and respond to toxic metal ions remain incompletely understood. Here, we uncover a previously unrecognized mechanism in Mycobacterium tuberculosis, the causative agent of tuberculosis, which assembles dynamic, membrane-associated platforms organized by PacL proteins to mediate resistance to multiple metals. The small membrane-associated proteins PacL1, PacL2, and PacL3 coordinate the clustering of P-type ATPase pumps, namely CtpC, CtpG, and CtpV, into functional complexes that we term effluxosomes. Using single-particle tracking, we reveal distinct dynamic populations, with highly mobile PacL proteins integrating into more slowly mobile effluxosomes. PacL proteins stabilize CtpC and CtpG within these assemblies, promoting cross-resistance to zinc and cadmium, with PacL1 acting as a multi-substrate metallochaperone that binds zinc, cadmium, and copper via a conserved C-terminal motif. Single-molecule-based super-resolution microscopy shows that conserved residues within the PacL transmembrane domain are essential for effluxosome assembly. Strikingly, proximity labeling reveals a broad PacL1 interaction network, suggesting that effluxosomes contribute to a wider stress adaptation program. These findings establish effluxosomes as dynamic membrane machineries that orchestrate coordinated multi-metal resistance in M. tuberculosis, opening new avenues for antimicrobial targeting.