Molecular Biology of a Surface-Exposed Protein Family in Bartonella bacilliformis
Research Project Description
Bartonella bacilliformis causes Carrión’s disease, a potentially life-threatening infection transmitted by sand flies in the Andes. The illness has a mortality rate of 88% when untreated and 10% when treated. Diagnostics and control measures are underdeveloped and no vaccine is available. The range of the pathogen is increasing with nearly 1.7 million people at risk, but little is known about the pathogenesis of B. bacilliformis. A recent study found a paralogous gene family (impA) that is solely shared between the Bartonella and Leptospira genera. This is intriguing since these bacteria are phylogenetically unrelated. The gene family is suspected to affect the virulence of the bacterium, based on the findings that it was one of a few that were mutated during attenuation and all members of the gene family were up-regulated considerably during leptospirosis in a mouse model. The objective of our research is to investigate the function of the paralogous gene family and elucidate why both Leptospira and Bartonella have maintained it. This will lead to a better understanding of Bartonella’s pathogenesis and indicate if the proteins are potential virulence factors. Determining the cellular location of the ImpA proteins will give us a better understanding of their function. To this end, a fragment of one impA gene (BARBAKC583_0452) was cloned into an expression vector (pQE31) to generate a fusion protein with a His6 tag. The recombinant peptide was expressed and purified from E. coli and used to generate rabbit polyclonal antibodies. The antibodies were tested for seroreactivity against the Bb0452 peptide on western blots and reacted positively. However, the antibodies did not detect the protein in cell lysates. We are currently determining if the protein is only expressed under certain growth conditions. Once the protein is expressed, we will localize it using cell fractionation techniques and the anti-Bb0452 antibodies. The paper on this research can be found here.
Mike Minnick, Professor of Microbiology, Division of Biological Sciences
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