Kupyaphores are zinc homeostatic metallophores required for colonization of <i>Mycobacterium tuberculosis</i>

Abstract

<i>Mycobacterium tuberculosis</i> (<i>Mtb</i>) endures a combination of metal scarcity and toxicity throughout the human infection cycle, contributing to complex clinical manifestations. Pathogens counteract this paradoxical dysmetallostasis by producing specialized metal trafficking systems. Capture of extracellular metal by siderophores is a widely accepted mode of iron acquisition, and <i>Mtb</i> iron-chelating siderophores, mycobactin, have been known since 1965. Currently, it is not known whether <i>Mtb</i> produces zinc scavenging molecules. Here, we characterize low-molecular-weight zinc-binding compounds secreted and imported by <i>Mtb</i> for zinc acquisition. These molecules, termed kupyaphores, are produced by a 10.8 kbp biosynthetic cluster and consists of a dipeptide core of ornithine and phenylalaninol, where amino groups are acylated with isonitrile-containing fatty acyl chains. Kupyaphores are stringently regulated and support <i>Mtb</i> survival under both nutritional deprivation and intoxication conditions. A kupyaphore-deficient <i>Mtb</i> strain is unable to mobilize sufficient zinc and shows reduced fitness upon infection. We observed early induction of kupyaphores in <i>Mtb</i>-infected mice lungs after infection, and these metabolites disappeared after 2 wk. Furthermore, we identify an <i>Mtb</i>-encoded isonitrile hydratase, which can possibly mediate intracellular zinc release through covalent modification of the isonitrile group of kupyaphores. <i>Mtb</i> clinical strains also produce kupyaphores during early passages. Our study thus uncovers a previously unknown zinc acquisition strategy of <i>Mtb</i> that could modulate host-pathogen interactions and disease outcome.