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Bacterial effector binds host cell adenylyl cyclase to potentiate Gαs-dependent cAMP production

Author:
Pulliainen, Arto T., Pieles, Kathrin, Brand, Cameron S., Hauert, Barbara, Böhm, Alex, Quebatte, Maxime, Wepf, Alexander, Gstaiger, Matthias, Aebersold, Ruedi, Dessauer, Carmen W., Dehio, Christoph
Source:
Proceedings of the National Academy of Sciences of the United States of America 2012 v.109 no.24 pp. 9581-9586
ISSN:
0027-8424
Subject:
Bartonella henselae, Escherichia coli, adenosine diphosphate, adenylate cyclase, apoptosis, cholera, cyclic AMP, endothelial cells, endothelium, fluorescence, humans, pathogenesis, pertussis toxin, proteins, proteomics, surface plasmon resonance
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 α-subunit of the AC-stimulating G protein (Gαs) 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 Gαs and BepA in Escherichia coli ; (ii) in vitro AC assays with membrane-anchored full-length human AC and recombinant BepA and Gαs; (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 Gαs-dependent cAMP production. As opposed to the known microbial mechanisms, such as ADP ribosylation of G protein α-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 Gαs. We propose that this mechanism contributes to the persistence of Bartonella henselae in the chronically infected vascular endothelium.
Agid:
1721141