Cell cycle-dependent variation in endocytosis drives phenotypic diversity in M. tuberculosis

Cell-to-cell heterogeneity is a hallmark of biology, yet how host variability shapes intracellular pathogen phenotypes is unclear. Using single cell approaches and redox-sensitive Mycobacterium tuberculosis reporters, we reveal that interphase-driven shifts in endocytic capacity create distinct intracellular niches. Bacilli residing in high-endocytic G2 cells adopt more oxidized redox states, whereas those in low-endocytic G1 cells remain reduced, generating phenotypic diversity within a single infected population. Experimental manipulation of host cell cycle stage reprograms endocytic capacity and intrabacterial redox, establishing a causal link between host state and pathogen diversification. Notably, the finding that the cell cycle regulates endocytic capacity constitutes a fundamental cell-biological discovery with broad implications. This variability persists in post-differentiated macrophages, indicating that proliferative history imprints functional diversity onto innate immune cells. Together, these results identify interphase-regulated endocytosis as a host-intrinsic mechanism that shapes Mycobacterium tuberculosis phenotypes and suggest new host-directed avenues to influence infection trajectories and persistence.