Brucella abortus MFP: A Trimeric Coiled-Coil Protein with Membrane Fusogenic Activity

Abstract

The bacterial genus Brucella consists of a group of facultative intracellular pathogens which produces abortion and infertility in animals and a chronic debilitating febrile illness in humans. BMFP is a basic protein of Brucella abortus that belongs to a highly conserved group of homologue proteins of unknown structure and function in proteobacteria (COG2960). In this study, we report the structural and biochemical characterization of this protein. We found that BMFP has two structural domains: a carboxylterminal coiled-coil domain through which the protein self-associates as a trimer and a natively disordered amino-terminal domain which has propensity to adopt an amphipathic R-helical structure. This natively unfolded domain undergoes a structural rearrangement from unfolded to R-helix in the presence of high ionic strength, acidic pH, detergents, and phospholipid vesicles. Moreover, we demonstrated that the interaction of BMFP with phospholipid vesicles promotes in vitro membrane fusion. These results contribute to the elucidation of the structural and functional properties of this protein and its homologues present in most proteobacteria