PMID:11736996

Citation	Suárez, M, González-Zorn, B, Vega, Y, Chico-Calero, I and Vázquez-Boland, JA (2001) A role for ActA in epithelial cell invasion by Listeria monocytogenes. Cell. Microbiol. 3:853-64
Abstract	We assessed the role of the actin-polymerizing protein, ActA, in host cell invasion by Listeria monocytogenes. An in frame DeltaactA mutant was constructed in a hyperinvasive strain of prfA* genotype, in which all genes of the PrfA-dependent virulence regulon, including actA, are highly expressed in vitro. Loss of ActA production in prfA* bacteria reduced entry into Caco-2, HeLa, MDCK and Vero epithelial cells to basal levels. Reintroduction of actA into the DeltaactA prfA* mutant fully restored invasiveness, demonstrating that ActA is involved in epithelial cell invasion. ActA did not contribute to internalization by COS-1 fibroblasts and Hepa 1-6 hepatocytes. Expression of actA in Listeria innocua was sufficient to promote entry of this non-invasive species into epithelial cell lines, but not into COS-1 and Hepa 1-6 cells, indicating that ActA directs an internalization pathway specific for epithelial cells. Scanning electron microscopy of infected Caco-2 human enterocytes suggested that this pathway involves microvilli. prfA* bacteria, but not wild-type bacteria (which express PrfA-dependent genes very weakly in vitro) or prfA* DeltaactA bacteria, efficiently invaded differentiated Caco-2 cells via their apical surface. Microvilli played an active role in the phagocytosis of the prfA* strain, and actA was required for their remodelling into pseudopods mediating bacterial uptake. Thus, ActA appears to be a multifunctional virulence factor involved in two important aspects of Listeria pathogenesis: actin-based motility and host cell tropism and invasion.
Links	PubMed
Keywords	Amino Acid Sequence; Animals; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Bacterial Proteins/physiology; Base Sequence; COS Cells; Caco-2 Cells; Cell Line; Cercopithecus aethiops; DNA, Bacterial; Dogs; Epithelial Cells/cytology; Epithelial Cells/metabolism; Epithelial Cells/microbiology; Gene Expression; HeLa Cells; Humans; Listeria monocytogenes/isolation & purification; Listeria monocytogenes/metabolism; Listeria monocytogenes/physiology; Listeria monocytogenes/ultrastructure; Membrane Proteins/genetics; Membrane Proteins/metabolism; Membrane Proteins/physiology; Microscopy, Electron, Scanning/methods; Molecular Sequence Data; Mutagenesis; Peptide Termination Factors; Trans-Activators; Vero Cells
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
LISMO:ACTA		GO:0009405 : pathogenesis	ECO:0000315:		P		Figure 2: Percentage of invaded cells using various mutants of ActA.	complete

References

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