期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2012
卷号：109
期号：24
页码：9581-9586
DOI：10.1073/pnas.1117651109
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：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 (Gs) 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 Gs and BepA in Escherichia coli; (ii) in vitro AC assays with membrane-anchored full-length human AC and recombinant BepA and Gs; (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 Gs-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 Gs. We propose that this mechanism contributes to the persistence of Bartonella henselae in the chronically infected vascular endothelium.
关键词：bacterial infection ; apoptosis ; tumorigenesis ; type IV secretion
