Our laboratory studies Borrelia spirochetes and the diseases they cause, Lyme disease and relapsing fever. After transmission of Borrelia through bites of certain tick species, both Lyme disease and relapsing fever are characterized by the spread of bacteria via the bloodstream, which may lead to the infection of multiple organs such as the skin, heart, joints, and brain. While these pathogenic processes are not yet well understood on the molecular level, the involved virulence factors identified so far have been surface lipoproteins.
A first project identifies lipoprotein sequence determinants, membrane protein complexes and chaperones involved in spirochete lipoprotein export. We are currently using fluorescent proteins as markers for protein localization in live Borrelia cells to determine the sorting signals for surface and subsurface lipoproteins. Using biochemical and novel genetic approaches, we are also in the process of characterizing the lipoprotein export machinery in Borrelia burgdorferi, the Lyme disease spirochete. These studies will ultimately help in the design of novel intervention strategies for spirochetal infections.
A related second research project focuses on two families of relapsing fever Borrelia surface lipoproteins at the host-pathogen interface: the variable small (Vsp) and variable large (Vlp) proteins. These two protein families are essential for bacterial lifestyle: By antigenic variation of Vsps and Vlps, the spirochetes are able to continually change their coat, which allows them to repeatedly evade the host antibody response. In addition, experimental relapsing fever in mice has shown that the expression of different Vsps targets the bacteria to different organs, such as heart, joints or brain. The long term research goals are to elucidate Borrelia-host interactions by integrating functional data and structural information on the proteins involved. Specific projects include the biochemical and biophysical characterization of Vsp and Vlp proteins, leading towards the determination of their three-dimensional structures; and the identification of ligand-binding domains and antibody epitopes in vitro and in vivo, using a novel Borrelia lipoprotein surface display system.
Whetstine C.R., Slusser J.G., Zückert W.R. 21 August 2009. Development of a single plasmid-based regulatable gene expression system in Borrelia burgdorferi. Appl. Environ. Microbiol. doi:10.1128/AEM.02825-08.
von Lackum K., Ollison K.M., Bykowski T., Nowalk A.J., Hughes J.L., Carroll J.A., Zückert W.R. & Stevenson B. (2007) Regulated synthesis of the Borrelia burgdorferi inner-membrane lipoprotein IpLA7 (P22, P22-A) during the Lyme disease spirochete's mammal-tick infectious cycle. Microbiology, 153:1361-1371.
Lawson C.L., Yung B.H., Barbour A.G. & Zückert W.R. (2006) Crystal structure of neurotropism-associated variable surface protein 1 (Vsp1) of Borrelia turicatae. J. Bacteriol. 188:4522-4530.
Schulze R.J. & Zückert W.R. (2006) Borrelia burgdorferi lipoproteins are secreted to the outer surface by default. Mol. Microbiol. 59:1473-1484.
Lodoño D., Bai Y., Zückert W.R., Gelderblom H. & Cadavid D. (2005) Cardiac apoptosis in severe relapsing fever borreliosis. Infect. Immun. 73:7669-7676.
Zückert W.R., Lloyd J.E., Stewart P.E., Rosa P.A. & Barbour A.G. (2004) Cross-species surface display of spirochetal lipoproteins by recombinant Borrelia burgdorferi. Infect. Immun. 72:1463-1469.
National Institutes of Health, Grant R01-AI063261: Lipoprotein Transport in Borrelia Spirochetes, 2006-2011, $250,000 direct costs per year.
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The University of Kansas Medical Center