The Outer membrane factor of Brucella is involved in antimicrobial resistance and virulence

POSADAS, D. M.; MARTÍN, F A; SABIO GARCÍA, M J; SPERA, J M; CRAVERO, S; ZORREGUIETA, A

Centro Cultural Parque de España - Rosario, Argentina

Congreso; XLII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular.; 2006

SAIB

Brucella spp., like other pathogens, must cope with the environment of diverse host niches during the infection process.In doing this, pathogens evolved different type of transport systems to help them survive and disseminate within the host. Members of the Outer Membrane Factor (OMF) in association with two inner-membrane proteins were shown to be involved inthe export of  chemically diverse molecules. The role of proteins from this family was little explored in Brucella; to analyze its biological relevance we performed heterologous complementation assays: the gene encoding the unique B. suis OMF protein (Bep) was cloned and expressed in the tolC mutant of E. coli. Bep fully complemented the resistance to drugs such as chloramphenicol and acriflavine but was incapable to restore hemolysin secretion in this mutant. An insertion mutant was constructed in B. suis and the sensitivity to several drugs was analyzed, as well as the virulence in diverse models; the mutation in the bep gene strongly affected the resistance phenotype to bile salts and toxic chemicals and significantly decreased the resistance to antibiotics such as erythromycin, tetracycline and norfloxacin. Moreover, the bep mutant of B. suis was attenuated in the mice model. Taking together, these results suggest that in B. suis, efflux processes that are Bep dependent contribute to survival inside the host.