The enolase of Borrelia burgdorferi is a plasminogen receptor released in outer membrane vesicles.

Department of Molecular Genetics and Microbiology, Center for Infectious Diseases, Stony Brook University, Stony Brook, New York, USA.
Infection and immunity (Impact Factor: 4.16). 11/2011; 80(1):359-68. DOI: 10.1128/IAI.05836-11
Source: PubMed

ABSTRACT The agent of Lyme disease, Borrelia burgdorferi, has a number of outer membrane proteins that are differentially regulated during its life cycle. In addition to their physiological functions in the organism, these proteins also likely serve different functions in invasiveness and immune evasion. In borreliae, as well as in other bacteria, a number of membrane proteins have been implicated in binding plasminogen. The activation and transformation of plasminogen into its proteolytically active form, plasmin, enhances the ability of the bacteria to disseminate in the host. Outer membrane vesicles of B. burgdorferi contain enolase, a glycolytic-cycle enzyme that catalyzes 2-phosphoglycerate to form phosphoenolpyruvate, which is also a known plasminogen receptor in Gram-positive bacteria. The enolase was cloned, expressed, purified, and used to generate rabbit antienolase serum. The enolase binds plasminogen in a lysine-dependent manner but not through ionic interactions. Although it is present in the outer membrane, microscopy and proteinase K treatment showed that enolase does not appear to be exposed on the surface. However, enolase in the outer membrane vesicles is accessible to proteolytic degradation by proteinase K. Samples from experimentally and tick-infected mice and rabbits as well as from Lyme disease patients exhibit recognition of enolase in serologic assays. Thus, this immunogenic plasminogen receptor released in outer membrane vesicles could be responsible for external proteolysis in the pericellular environment and have roles in nutrition and in enhancing dissemination.

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Available from: Alvaro Toledo, Jul 30, 2015
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    • "In contrast, a third group found BB0337 in outer membrane vesicles, but did not detect enolase on the outer surface of B. burgdorferi by proteinase K digestion or by electron microscopy (Toledo et al., 2012). In addition, Toledo et al. demonstrated that enolase was recognized by host antibodies from tick-infected mice, rabbits, and human Lyme disease patients (Toledo et al., 2012). "
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    • "After transport from the cytosol across the inner membrane via the Sec translocation pathway, they are released into the periplasm upon signal peptide cleavage, where they function in their characteristic roles (Lipinska et al., 1990; Waller and Sauer, 1996; Dalbey et al., 2012). HtrABb first drew our interest when it was found to be a constituent of B. burgdorferi vesicles (Toledo et al., 2012). Many Gram-negative bacteria release vesicles, which contain both outer membrane and periplasmic elements, as part of the bacterial stress response (McBroom and Kuehn, 2007). "
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    • "[15] [32] [33]. In addition, exosomes from Leishmania spp. as well other exosomes or outer membrane vesicles from other cells [15] [30] [34] [35] contain enolase, a plasminogen binding protein in many cells and microorganisms including L. mexicana [8]. Indeed, the secreted membrane vesicle preparations in this study contained this protein (Fig. 2C). "
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