Salmonella Inhibits Retrograde Trafficking of Mannose-6-Phosphate Receptors and Lysosome Function

Subversive Salmonella Salmonella is one of the most intensively studied bacterial pathogens. The Salmonella -containing vacuole (SCV) has a paradoxical lysosome-like composition: On one hand, the SCV membrane is highly enriched in lysosomal membrane glycoproteins and SCVs are accessible to endolysosomal content, but on the other hand, SCV lumen is relatively devoid of lysosomal hydrolytic enzymes that are delivered by the mannose-6-phosphate receptor pathway. McGourty et al. (p. 963 ) resolve this paradox by showing that the Salmonella effector SifA interferes with the trafficking of mannose-6-phosphate receptors. This causes misrouting and secretion of lysosomal enzymes and reduces the hydrolytic activity of lysosomes. Intracellular growth of Salmonella was reduced in cells with enhanced lysosomal enzyme activity.