Funtional characterization of a B. suis ABC-MFP translocase

FERNANDO A. MARTIN; DIANA POSADAS; M. VICTORIA DELPINO; PABLO C. BALDI; ELEONORA CAMPOS; ANGELES ZORREGUIETA

Mexico

Congreso; 58 th Brucellosis 2005. International Research Conference.; 2005

Abstract Gram negative bacteria have evolved transport complexes that export macromolecules and toxic substances across both inner and outer membranes in a single energy cupled step. The process requires a cytoplasmic membrane protein (ABC or RND), an accessory protein (MFP), and an outer membrane factor (OMF) of the TolC family. The roles of these systems in Brucella spp. remain unexplored. Both protein export an efflux of toxic compounds may be crucial in survival and pathogenicity in  Brucella spp. Three putative ABC-MFP systems have been identified in the B. suis genome. Phylogenetic analysis of the MFP components placed them close to those involved in drug efflux. In order to study the possible roles of the ABC-MFP systems, heterologous complementation studies were performed on an E. coli acrAB hypersensitive mutant, which is affected in drug efflux. Drug efflux was analized by measuring the minimun inhibitory concentration (MIC) of different compounds such as detergents, drugs and antibiotics. One of the transport loci (eflA1-eflB1) conferred to the E coli acrAB mutant, a clear reduction of rhodamine 6G accumulation. In addition, EflA1-EflB1 was unable to restore drug resistence in an acrAB-tolC double mutant of E coli indicating that efflux by EflA1-EflB1 en E. coli is OMF dependent. These results show that the EflA1-EflB1 complex is capable of promoting efflux of toxic compounds. However, disruption of elfA1 in B. suis din not decrease the level of resistance od Brucella to several drugs, suggesting that there may be additional systems which could also contribute to drug efflux.