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Yersinia virulence factor YopM induces sustained RSK activation by interfering with dephosphorylation

Moritz Hentschke1, Laura Berneking, Cristina Belmar Campos

  • 1Institute of Medical Microbiology, Virology and Hygiene, University Medical Center Eppendorf, Hamburg, Germany. jbaltzer@mta.ca

Plos One
|October 20, 2010
PubMed
Abstract

Insights

Pathogenic Yersinia bacteria use the YopM effector protein to block the dephosphorylation of RSK kinases. This novel mechanism sustains RSK activation, aiding bacterial survival during infection.

Area of Science:

  • Microbiology
  • Cellular Biology
  • Immunology

Background:

  • Pathogenic Yersinia species inject effector proteins (Yops) into host cells to subvert immune responses and ensure bacterial survival.
  • YopM is a critical virulence factor, and its absence significantly reduces Yersinia's pathogenicity.
  • YopM has been previously implicated in forming complexes with and activating PKN2 and RSK1 kinases in host cells.

Purpose of the Study:

  • To investigate the interaction of YopM with protein kinases PKN and RSK in a near-physiological setting.
  • To elucidate the mechanism by which YopM influences RSK activity during Yersinia infection.
  • To explore the potential role of YopM in modulating host cell signaling pathways.

Main Methods:

  • Utilized a double-affinity-tagged YopM translocated into J774A.1 macrophages via Yersinia's type three secretion system.
  • Analyzed YopM interactions with PKN and RSK isoforms in transfected and infected cells.
  • Performed ATP-depletion assays and in vitro studies with purified components to assess phosphatase activity.

Main Results:

  • Confirmed YopM interaction with PKN2 and RSK1, and identified associations with additional PKN and RSK isoforms.
  • Demonstrated that YopM induces sustained RSK phosphorylation at activation sites (serine-380 and serine-221), independent of upstream signaling.
  • Showed that YopM directly inhibits RSK dephosphorylation by shielding RSK isoforms from phosphatase activity.

Conclusions:

  • YopM promotes sustained RSK activation during Yersinia infection by preventing the dephosphorylation of key activation sites.
  • This represents a novel mechanism employed by a bacterial virulence factor to manipulate host cell signaling.
  • The findings offer new insights into Yersinia pathogenesis and host-pathogen interactions.

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