Mycobacterial Lipids Orchestrate Infection Stage-Specific Remodeling of the Host Actin Cytoskeleton

Abstract The actin cytoskeleton is a central target of host–pathogen interactions, yet how distinct microbial factors engage specific actin regulatory pathways remains poorly understood. Here, we show that mycobacterial envelope lipids directly modulate host actin dynamics through distinct molecular mechanisms. Using quantitative imaging and lipidomic analysis, we demonstrate that sulfoglycolipids (SL-1) and phenolic glycolipid-1 (PGL-1) promote actin depolymerization via cofilin-mediated severing, whereas phthiocerol dimycocerosate (PDIM) and trehalose dimycolate (TDM) induce actin polymerization through activation of the WASP–Arp2/3 pathway. These lipid-specific effects correspond to changes in lipid abundance across infection stages, linking cytoskeletal remodeling to temporal regulation of infection. Functionally, actin depolymerization enhances bacterial uptake or release depending on lipid context, while polymerization differentially impacts host cell entry and intracellular persistence. Together, our findings establish that mycobacterial lipids act as molecular determinants of cytoskeletal organization, engaging distinct actin regulatory pathways to shape infection dynamics.