Spirochetes of the genus Borrelia, the causative agents of vector-borne Lyme borreliosis (LB) and relapsing fever (RF), display throughout their lifecycle a variety of abundant lipoproteins with distinct biological functions. Irrespective of the regulatory mechanisms governing the expression of different lipoproteins in different environments, the successful deployment of these spirochetal virulence factors hinges on (i) an efficient lipoprotein modification and transport system, and (ii) an accurate lipoprotein sorting machinery. The overall objective of this proposal is to gain key insights into these two important underlying aspects of spirochetal pathogenesis using the LB spirochete Borrelia burgdorferi as a model. Our preliminary studies indicate that Borrelia lipoproteins sorting signals localize to an N-terminal sequence of about ten residues after the N-terminal cysteine, yet differ from the ones characterized in E. coli. We have also begun to characterize B. burgdorferi BB0346 as a functional homolog of the periplasmic lipoprotein carrier LolA in E. coli. Protein homologs for molecular events in this pathway upstream, but not downstream of BB0346 were identified as well. We therefore hypothesize that (i) the Borrelia lipoprotein export machinery is similar to the one described in E. coli, but (ii) pathways at the outer membrane and (iii) the lipoprotein sorting rules diverge significantly from the ones described in other diderm bacteria. To test these hypotheses, we have formulated the following three specific aims: 1. To further define borrelial lipoprotein sorting signals by studying subcellular (mis)localization of fluorescent reporter proteins and lipoprotein mutants. 2. To further characterize the biological function of B. burgdorferi Lol protein homologs using co- immunoprecipitation, affinity purification, and complementation experiments. 3. To identify and characterize other components of the borrelial lipoprotein export machinery using novel mutagenic and proteomic approaches. These studies will (i) significantly increase our understanding of spirochetal virulence, (ii) shed more light on the evolution of bacterial protein export mechanisms in general, and (iii) may yield important clues for the design of future intervention strategies.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI063261-05
Application #
7870484
Study Section
Prokaryotic Cell and Molecular Biology Study Section (PCMB)
Program Officer
Breen, Joseph J
Project Start
2006-06-01
Project End
2012-05-31
Budget Start
2010-06-01
Budget End
2012-05-31
Support Year
5
Fiscal Year
2010
Total Cost
$346,563
Indirect Cost
Name
University of Kansas
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
016060860
City
Kansas City
State
KS
Country
United States
Zip Code
66160
Dowdell, Alexander S; Murphy, Maxwell D; Azodi, Christina et al. (2017) Comprehensive Spatial Analysis of the Borrelia burgdorferi Lipoproteome Reveals a Compartmentalization Bias toward the Bacterial Surface. J Bacteriol 199:
Jutras, Brandon L; Verma, Ashutosh; Adams, Claire A et al. (2012) BpaB and EbfC DNA-binding proteins regulate production of the Lyme disease spirochete's infection-associated Erp surface proteins. J Bacteriol 194:778-86
Kumru, Ozan S; Bunikis, Ignas; Sorokina, Irina et al. (2011) Specificity and role of the Borrelia burgdorferi CtpA protease in outer membrane protein processing. J Bacteriol 193:5759-65
Chen, Shiyong; Zuckert, Wolfram R (2011) Probing the Borrelia burgdorferi surface lipoprotein secretion pathway using a conditionally folding protein domain. J Bacteriol 193:6724-32
Chen, Shiyong; Kumru, Ozan S; Zuckert, Wolfram R (2011) Determination of Borrelia surface lipoprotein anchor topology by surface proteolysis. J Bacteriol 193:6379-83
Kumru, Ozan S; Schulze, Ryan J; Rodnin, Mykola V et al. (2011) Surface localization determinants of Borrelia OspC/Vsp family lipoproteins. J Bacteriol 193:2814-25
Gandhi, Gaurav; Londono, Diana; Whetstine, Christine R et al. (2010) Interaction of variable bacterial outer membrane lipoproteins with brain endothelium. PLoS One 5:e13257
Kumru, Ozan S; Schulze, Ryan J; Slusser, Joyce G et al. (2010) Development and validation of a FACS-based lipoprotein localization screen in the Lyme disease spirochete Borrelia burgdorferi. BMC Microbiol 10:277
Schulze, Ryan J; Chen, Shiyong; Kumru, Ozan S et al. (2010) Translocation of Borrelia burgdorferi surface lipoprotein OspA through the outer membrane requires an unfolded conformation and can initiate at the C-terminus. Mol Microbiol 76:1266-78
Whetstine, Christine R; Slusser, Joyce G; Zuckert, Wolfram R (2009) Development of a single-plasmid-based regulatable gene expression system for Borrelia burgdorferi. Appl Environ Microbiol 75:6553-8

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