Anaplasma phagocytophilum-occupied vacuole interactions with the host cell cytoskeleton

Hilary K. Truchan, Chelsea L. Cockburn, Levi J. May, Lauren VieBrock, Jason A. Carlyon*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Anaplasma phagocytophilum is an obligate intracellular bacterial pathogen of humans and animals. The A. phagocytophium-occupied vacuole (ApV) is a critical host-pathogen interface. Here, we report that the intermediate filaments, keratin and vimentin, assemble on the ApV early and remain associated with the ApV throughout infection. Microtubules localize to the ApV to a lesser extent. Vimentin, keratin-8, and keratin-18 but not tubulin expression is upregulated in A. phagocytophilum infected cells. SUMO-2/3 but not SUMO-1 colocalizes with vimentin filaments that surround ApVs. PolySUMOylation of vimentin by SUMO-2/3 but not SUMO-1 decreases vimentin solubility. Consistent with this, more vimentin exists in an insoluble state in A. phagocytophilum infected cells than in uninfected cells. Knocking down the SUMO-conjugating enzyme, Ubc9, abrogates vimentin assembly at the ApV but has no effect on the bacterial load. Bacterial protein synthesis is dispensable for maintaining vimentin and SUMO-2/3 at the ApV. Withaferin A, which inhibits soluble vimentin, reduces vimentin recruitment to the ApV, optimal ApV formation, and the bacterial load when administered prior to infection but is ineffective once vimentin has assembled on the ApV. Thus, A. phagocytophilum modulates cytoskeletal component expression and co-opts polySUMOylated vimentin to aid construction of its vacuolar niche and promote optimal survival.

Original languageEnglish (US)
Article number25
JournalVeterinary Sciences
Issue number3
StatePublished - Sep 1 2016


  • Anaplasma phagocytophilum
  • Cytoskeleton
  • SUMOylation
  • Vacuole-adapted bacteria
  • Vimentin

ASJC Scopus subject areas

  • veterinary(all)


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