Effector proteins support the asymmetric apportioning of Salmonella during cytokinesis

ABSTRACT

Salmonella-infected cells are characterized by the presence of intra-cellular membranous tubules that emerge from bacterial vacuoles and extend along microtubules. The formation of Salmonella-induced tubules depends on the Salmonella pathogenicity island 2-encoded type III secretion system (T3SS-2) that translocates bacterial effector proteins inside host cells. Effector proteins have enzymatic activities or allow for hijacking of cellular functions. The role of Salmonella-induced tubules in virulence remains unclear but their absence is correlated with virulence defects. This study describes the presence of inter-cellular tubules that arise between daughter cells during cytokinesis. Inter-cellular tubules connect bacterial vacuoles originally present in the parent cell and that have been apportioned between daughters. Their formation requires a functional T3SS-2 and effector proteins. Our data establish a correlation between the formation of inter-cellular tubules and the asymmetric distribution of bacterial vacuoles in daughters. Thus, by manipulating the distribution of bacteria in cytokinetic cells, Salmonella T3SS-2 effector proteins may increase bacterial spreading and the systemic character of the infection.

KEYWORDS:

• effector protein
• eukaryotic cell cycle
• Salmonella
• type 3 secretion system
• virulence

This article is referred to by:

Divide and conquer: Salmonella move into both daughter cells during mitosis

Abbreviations

ICT	=	inter-cellular tubules
p.i.	=	post-infection
SCV	=	Salmonella-containing vacuole
SIT	=	Salmonella-induced tubules
T3SS	=	Salmonella type 3 secretion system

Disclosure of potential conflicts of interest

No potential conflicts of interest were disclosed.

Acknowledgments

We thank Steve Garvis for the critical reading of the manuscript and David W. Holden for providing bacterial strains.

Funding

YZ was supported by the China Scholarship Council. We acknowledge financial supports from n° ANR-10-INBS-04-01 France Bio Imaging, LabEx INFORM, and from the Fondation pour la Recherche Médicale (FRM SC).