Actin to trap bacteria

Abstract

Microbiology Salmonella bacteria cause tens of millions of cases of food-related illnesses every year. On infecting host cells, the bacterium injects virulence factors that induce rearrangements of the cytoskeleton to allow internalization inside a Salmonella -containing vacuole (SCV). Here, the bacteria replicate protected from the host immune system. Hahn et al. show that although the actin network is hijacked to allow bacterial entry, it is also part of a cellular defense system. Through proteomics analysis, the authors identified the kinase SIK2 as a central player in coordinating actin defenses. During bacterial infection, SIK2 is recruited to the SCV together with proteins involved in actin polymerization. SIK2 depletion allows the escape of bacteria from the SCV, which results in collapse of cortical actin structures. Thus, SIK2 coordinates an actin network that limits intracellular proliferation of Salmonella . Proc. Natl. Acad. Sci. U.S.A. 118 , e2024144118 (2021).