MapA: a protein involved in the envelope biogénesis of Brucella suis

RUIZ-RANWEZ, V.; POSADAS, D. M.; ESTEIN, S.; RUSSO, D.M; BIALER, M.G.; ABDIAN P.L.; ZORREGUIETA A.

Rosario

Congreso; L Reunión Anual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB); 2014

Sociedad Argentina de Investigaciones Bioquimicas y Biologia Molecular

Brucellae have cell envelopes with characteristic properties which make them more resistant to polycationic peptides and more permeable to hydrophobic compounds. It has been proposed that this would reflect an adaptation to intracellular parasitism. We have identified a gene of B. suis encoding a protein (MapA) predicted to localize to the cell envelope, which may have a role in the envelope biogenesis. The B. suis delta mapA mutant did not show differences compared to the parental strain regarding the pattern of outer membrane proteins, the growth curve in rich medium or under saline stress and tolerance to acidic pH or to complement present in porcine serum. Instead, the mutant was impaired in the ability to bind to HeLa cells. Besides, the mutant showed an enhanced sensitivity to Triton X-100, Polymyxin B and Lysozyme. Observation of the phenotype of delta mapA with acriflavine and the analysis of the LPS patterns by SDS-PAGE and silver staining  suggest that the O-antigen region of the LPS is not altered in the mutant. Interestingly, the colonies of the mutant in the presence of crystal violet showed a differential staining compared with the wild type. We propose that MapA plays a role in the integrity of the cell envelope. Since it is clear that a defective envelope could be linked with a reduced virulence, we are currently evaluating the virulence of the mutant using the murine model.