: a novel B. suis 1330 adhesin from the type II autotransporter family

RUIZ V., POSADAS D.M., AROCENA G, ABDIAN P., MARTIN F.A., SIEIRA R, ZORREGUIETA A.

Congreso; Brucellosis 2011, International Research Conference; Including the 64th Brucellosis Research Conference; 2011

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:none; mso-layout-grid-align:none; text-autospace:none; font-size:12.0pt; font-family:Arial; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:ES-AR; mso-fareast-language:ES-AR;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Some steps on the infection of Brucellae have been exhaustively studied while others such as adhesion and invasion to host cells remain poorly understood despite being essential for the pathogen’s infection. Based on bioinfomatical approaches we identified in Brucella suis 1330 genome several putative adhesins. In the present work we show partial characterization of one of them which belongs to the Type V Secretion System: AubE. To characterize this protein we obtained the strains of B. suis 1330 ΔaubE, and the complemented strain. We also expressed the protein in an E. coli strain which originally was non adherent nor invasive. In the case of the heterologous expression we cloned the entire gene with its own promoter in a plasmid of mid-number of copies which replicates in Brucella (pBBR1MCS). In all the experiments where we found the mutant strain had a different phenotype compared to the wild type, the complemented strain recovered the parental one. We have also produced specific antibodies with which we could verify that the protein is exposed on the bacterial surface, as it is expected in the case of adhesins. It has been previously shown that Brucellae is able to adhere to epithelial cell lines, and we have seen that B. suis ΔbtaE had a dramatical loss in its ability to attach and invade HeLa cells. Nevertheless the loss in the invasion seems to be consequence of the decrease of adhesion. We have not seen any differences in macrophages infection. In order to identify molecules which could act as receptors in the host cells surface, we evaluated adhesion to several components of the extracellular matrix of different eukaryotic cells. The results obtained in Brucella where consistent with those in E. coli: BtaE would interact with hialuronic acid. These results suggest that BtaE is involved in adhesion to eukaryotic cells, although there are more adhesins involved in this process that could act at the same time. This somehow shows how important this stage is during infection. Besides, understanding differences in adhesin activity and/or expression between Brucella species may contribute to a differential tissue tropism.