Cysteine reactivity profiling identifies host regulators of replication in human macrophages.

Innate immune cells such as monocytes and macrophages provide the earliest defense against infection by intracellular pathogens by initiating signaling pathways and restricting pathogen replication. However, the full complement of proteins that mediate cell-autonomous immunity remains incompletely defined. Here, we applied cysteine-directed activity-based protein profiling (ABPP) to map proteome-wide cysteine reactivity changes in THP-1 monocytes and primary human monocyte-derived macrophages during (Mtb) infection. Across both cell types, we quantified 148 cysteine residues with altered reactivity. Genetic perturbation of a subset of proteins harboring these changes significantly impacted Mtb replication, revealing functional links between site-specific cysteine reactivity and antimicrobial defense. These data define previously unrecognized host protein changes during Mtb infection and provide a resource for investigating post-translational events that regulate innate immune responses to intracellular bacteria.