Zückert, Pilot Project Summary

The overall goal of the proposal is to identify novel small molecule inhibitors of bacterial envelope biogenesis that will yield novel molecular tools to dissect biogenesis pathways and may lead to a new generation of antimicrobials. In addition to providing novel intervention strategies for infectious diseases, the work will shed further light on the secretion mechanisms of major bacterial envelope proteins. Our model organism, the Lyme disease spirochete Borrelia burgdorferi, lacks lipopolysaccharide (LPS), a major surface component of the outer membrane of other diderm bacteria such as the gram-negative Escherichia coli. Instead, B. burgdorferi expresses an extraordinary number of outer membrane lipoproteins with various crucial functions in transmission, colonization and persistence. Yet, our understanding of lipoprotein secretion pathways remains limited. We have identified several components of the B. burgdorferi lipoprotein secretion pathway, including components of a partial Lol (Lipoprotein outer membrane localization) pathway. We have solved the structure of the B. burgdorferi periplasmic lipoprotein carrier/chaperone LolA and are now beginning a detailed structure-function analysis. In this 1-year collaborative pilot project, we will initiate a screen for inhibitors of lipoprotein secretion in B. burgdorferi by adapting an already established 96-well-plate protein localization screen using fluorescent B. burgdorferi lipoprotein fusions. Initial lead compounds will be analyzed for their cognate targets and their spatiotemporal action affecting lipoprotein secretion by genomic sequencing and through established B. burgdorferi protein localization assays. Overall, the proposal will combine synergistic approaches to yield novel information that will significantly impact our understanding of bacterial protein secretion in a medically important model organism.