BtaE: a polar adhesin involved in binding of to host cells and virulence in mouse Brucella suis

Abstract

Increasing evidence indicates that adhesion of spp. to host cells is an important step to establish infection. We have previously shown that an unipolar type I monomeric autotransporter (BmaC) mediates the binding of to host cells through cellassociated fibronectin. Genome analysis shows that the genome encodes several additional potential adhesins. In this work we show that a protein from the Trimeric Autotransporter Family named as BtaE is involved in the binding of to hyaluronic acid and fibronectin. The mutant was: impaired in the ability to bind to host cells, outcompeted by the wild type strain in co-infections experiments, and showed an attenuated phenotype in the mouse model. Similar to BmaC, the BtaE adhesin was only observed at one of the cell poles. In and other - proteobacteria, the two daughter cells generated by asymmetric division are differentiated bacteria displaying different pole markers. Using pole markers we observed that BtaE is associated with the new pole. Furthermore, BmaC was also found to be localized to the same (new) pole, suggesting that adhesins are located at the new pole of the bacteria at a particular stage of the cell cycle.