Bacterial effector binds host cell adenylyl cyclase to potentiate G?s-dependent cAMP production.

ABSTRACT: Subversion of host organism cAMP signaling is an efficient and widespread mechanism of microbial pathogenesis. Bartonella effector protein A (BepA) of vasculotumorigenic Bartonella henselae protects the infected human endothelial cells against apoptotic stimuli by elevation of cellular cAMP levels by an as yet unknown mechanism. Here, adenylyl cyclase (AC) and the ?-subunit of the AC-stimulating G protein (G?s) were identified as potential cellular target proteins for BepA by gel-free proteomics. Results of the proteomics screen were evaluated for physical and functional interaction by: (i) a heterologous in vivo coexpression system, where human AC activity was reconstituted under the regulation of G?s and BepA in Escherichia coli; (ii) in vitro AC assays with membrane-anchored full-length human AC and recombinant BepA and G?s; (iii) surface plasmon resonance experiments; and (iv) an in vivo fluorescence bimolecular complementation-analysis. The data demonstrate that BepA directly binds host cell AC to potentiate the G?s-dependent cAMP production. As opposed to the known microbial mechanisms, such as ADP ribosylation of G protein ?-subunits by cholera and pertussis toxins, the fundamentally different BepA-mediated elevation of host cell cAMP concentration appears subtle and is dependent on the stimulus of a G protein-coupled receptor-released G?s. We propose that this mechanism contributes to the persistence of Bartonella henselae in the chronically infected vascular endothelium.

SUBMITTER: Pulliainen AT 

PROVIDER: S-EPMC3386119 | biostudies-literature | 2012 Jun

REPOSITORIES: biostudies-literature