title: BID-F1 and BID-F2 domains of Bartonella henselae effector protein BepF trigger together with BepC the formation of invasome structures.
abstract: The gram-negative, zoonotic pathogen Bartonella henselae (Bhe) translocates seven distinct Bartonella effector proteins (Beps) via the VirB/VirD4 type IV secretion system (T4SS) into human cells, thereby interfering with host cell signaling [1], [2]. In particular, the effector protein BepG alone or the combination of effector proteins BepC and BepF trigger massive F-actin rearrangements that lead to the establishment of invasome structures eventually resulting in the internalization of entire Bhe aggregates [2], [3]. In this report, we investigate the molecular function of the effector protein BepF in the eukaryotic host cell. We show that the N-terminal [E/T]PLYAT tyrosine phosphorylation motifs of BepF get phosphorylated upon translocation but do not contribute to invasome-mediated Bhe uptake. In contrast, we found that two of the three BID domains of BepF are capable to trigger invasome formation together with BepC, while a mutation of the WxxxE motif of the BID-F1 domain inhibited its ability to contribute to the formation of invasome structures. Next, we show that BepF function during invasome formation can be replaced by the over-expression of constitutive-active Rho GTPases Rac1 or Cdc42. Finally we demonstrate that BID-F1 and BID-F2 domains promote the formation of filopodia-like extensions in NIH 3T3 and HeLa cells as well as membrane protrusions in HeLa cells, suggesting a role for BepF in Rac1 and Cdc42 activation during the process of invasome formation.
authors: Focal Area Infection Biology, Biozentrum of the University of Basel, Basel, Switzerland.
authors: Matthias C
authors: MC
authors: Truttmann
authors: Patrick
authors: P
authors: Guye
authors: Christoph
authors: C
authors: Dehio
mesh_terms: D016917:Angiomatosis, Bacillary; D000818:Animals; D001426:Bacterial Proteins / Q000502:physiology*; D058947:Bacterial Secretion Systems / Q000502:physiology*; D018988:Bacterial Translocation; D018416:Bartonella henselae / Q000472:pathogenicity*; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D041681:NIH 3T3 Cells
chemical_list: D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems