Salmonella enterica Remodels the Host Cell Endosomal System for Efficient Intravacuolar Nutrition

Salmonella enterica is a facultative intracellular pathogen that survives and proliferates in the Salmonella-containing vacuole (SCV), yet how these vacuolar bacteria acquire nutrition remains to be determined. Intracellular Salmonella convert the host endosomal system into an extensive network of interconnected tubular vesicles, of which Salmonella-induced filaments (SIFs) are the most prominent. We found that membranes and lumen of SIFs and SCVs form a continuum, giving vacuolar Salmonella access to various types of endocytosed material. Membrane proteins and luminal content rapidly diffuse between SIFs and SCVs. Salmonella in SCVs without connection to SIFs have reduced access to endocytosed components. On a single-cell level, Salmonella within the SCV-SIF continuum were found to exhibit higher metabolic activity than vacuolar bacteria lacking SIFs. Our data demonstrate that formation of the SCV-SIF continuum allows Salmonella to bypass nutritional restriction in the intracellular environment by acquiring nutrients from the host cell endosomal system.