Roles of a TolC homologue in B. suis.

POSADAS, D. M.; MARTÍN, F A; CAMPOS E; ZORREGUIETA, A

Pinamar, Pcia de Buenos Aires

Congreso; 10th Congress Panamerican Association for Biochemistry and Molecular Biology. SAIB. 41 th Annual Meeting; 2005

Panamerican Association for Biochemistry and Molecular Biology y SAIB

The ability of Brucella to invade and survive within cells is the cornerstone of its virulence, yet the mechanisms underlying both processes are not clear. Membrane transport systems, able to export macromolecules and toxic substances, are crucial for bacterial survival and/or pathogenesis. Proteins from the Outer Membrane Factor (OMF) or TolC family have been implicated in several transport functions. In the Brucella suis genome only one member of the OMF family was identified by blast search. We analyzed the biological relevance of this unique OMF of B. suis (OmfBs). The E. coli TolC has the peculiarity to participate in several transport processes such as Colicin E1 uptake, a-hemolysin secretion and drug efflux.  We performed functional complementation studies in a tolC mutant of E. coli carrying the omfBs gene of B. suis under the control of an inducible promoter. While some of the TolC functions, such as colicin E1 uptake and efflux of acriflavine and chloramphenicol, were fully complemented by the omfBs gene of B. suis, protein secretion was not restored. Furthermore, an Spc(W) insertional  mutation in the omfBS   strongly affected the resistance phenotype of B. suis to different hydrophobic chemicals like rhodamine, acriflavine, erythromycin, carbenicillin and norfloxacin. Our results demonstrate that in B. suis the OmfBs protein participates in efflux of toxic compounds. In addition, the OmfBs protein may be potentially involved in other transport functions. Supported by  UBACyT X-245.