The mechanism and role of transient F-actin recruitment or F-actin “flashes” on phagosomes remains enigmatic. Here we provide a comprehensive characterization of F-actin flashing dynamics on phagosomes including receptor and signaling involvement. F-actin flashes predominate during the integrin-driven CR-mediated phagocytosis. F-actin flashes begin shortly after internalization and persist on phagosomes for ∼3 minutes before disassembling and reassembling several times within the first hour. Strikingly, the appearance of F-actin flashes on phagosomes coincides with RBC morphological deformation, lysis and occasional fission events. The cadence of flashes depends on particle stiffness and the F-actin networks on phagosomes are enriched in mechanosensitive components including focal adhesion proteins, RhoA and actomyosin. Inhibiting Arp2/3 and myosin IIA activity significantly reduces the frequency at which phagosome cargo becomes deformed during transient F-actin accumulation. At later time points, post-F-actin flashing, an enhanced degradation of phagosome contents is observed, compared to non-flashing phagosomes. Together these data suggest that actomyosin-driven phagosome contractions serve to physically disrupt malleable particles, a process akin to mastication, to enhance later enzymatic digestion.

Chlamydia trachomatis, the leading cause of bacterial sexually transmitted infections, disrupts cytokinesis and causes significant multinucleation in host cells. Here, we demonstrate that multinuclear cells that result from unsuccessful cell division contain significantly higher Golgi content, an important source of lipids for chlamydiae. Using immunofluorescence and fluorescent live cell imaging, we show that C. trachomatis in multinuclear cells indeed intercept Golgi-derived lipid faster than in mononuclear cells. Moreover, multinuclear cells enhance C. trachomatis inclusion growth and infectious particle formation. Together, these results indicate that C. trachomatis robustly position inclusions to the cell equator to disrupt host cell division in order to acquire host Golgi-derived lipids more quickly in multinucleated progeny cells.