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Bartonella henselae trimeric autotransporter adhesin BadA expression interferes with effector translocation by the VirB/D4 type IV secretion system

Lu, Y. Y. and Franz, B. and Truttmann, M. C. and Riess, T. and Gay-Fraret, J. and Faustmann, M. and Kempf, V. A. and Dehio, C.. (2012) Bartonella henselae trimeric autotransporter adhesin BadA expression interferes with effector translocation by the VirB/D4 type IV secretion system. Cellular microbiology, Vol. 15, H. 5 , S. 759–778.

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Official URL: http://edoc.unibas.ch/dok/A6056063

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Abstract

The gram-negative, zoonotic pathogen Bartonella henselae is the aetiologic agent of cat scratch disease, bacillary angiomatosis and peliosis hepatis in humans. Two pathogenicity factors of B. henselae - each displaying multiple functions in host cell interaction - have been characterized in greater detail: the trimeric autotransporter Bartonella adhesin A (BadA) and the type IV secretion system VirB/D4 (VirB/D4 T4SS). BadA mediates, e.g., binding to fibronectin (Fn), adherence to endothelial cells (ECs) and secretion of vascular endothelial growth factor (VEGF). VirB/D4 translocates several Bartonella effector proteins (Beps) into the cytoplasm of infected ECs, resulting, e.g., in uptake of bacterial aggregates via the invasome structure, inhibition of apoptosis and activation of a proangiogenic phenotype. Despite this knowledge of the individual activities of BadA or VirB/D4 it is unknown whether these major virulence factors affect each other in their specific activities. In this study, expression and function of BadA and VirB/D4 were analyzed in a variety of clinical B. henselae isolates. Data revealed that most isolates have lost expression of either BadA or VirB/D4 during in vitro passages. However, the phenotypic effects of co-expression of both virulence factors was studied in one clinical isolate that was found to stably co-express BadA and VirB/D4, as well as by ectopic expression of BadA in a strain expressing VirB/D4 but not BadA. BadA, which forms a dense layer on the bacterial surface, negatively affected VirB/D4-dependent Bep translocation and invasome formation by likely preventing close contact between the bacterial cell envelope and the host cell membrane. In contrast, BadA-dependent Fn binding, adhesion to ECs and VEGF secretion were not affected by a functional VirB/D4 T4SS. The obtained data imply that the essential virulence factors BadA and VirB/D4 are likely differentially expressed during different stages of the infection cycle of Bartonella.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Infection Biology > Molecular Microbiology (Dehio)
UniBasel Contributors:Dehio, Christoph and Lu, Yun-Yueh
Item Type:Article, refereed
Article Subtype:Research Article
Bibsysno:Link to catalogue
Publisher:Blackwell
ISSN:1462-5814
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:21 Jun 2013 12:29
Deposited On:21 Jun 2013 12:27

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