Structural investigation of Borrelia burgdorferi OspB, a bactericidal Fab target

Michael Becker, Jonas Bunikis, Barbara D. Lade, John J. Dunn, Alan G. Barbour, Catherine L. Lawson

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31 Scopus citations


Certain antibody Fab fragments directed against the C terminus of outer surface protein B (OspB), a major lipoprotein of the Lyme disease spirochete, Borrelia, burgdorferi, have the unusual property of being bactericidal even in the absence of complement. We report here x-ray crystal structures of a C-terminal fragment of B. burgdorferi OspB, which spans residues 152-296, alone at 2.0-Å resolution, and in a complex with the bactericidal Fab H6831 at 2.6-Å resolution. The H6831 epitope is topologically analogous to the LA-2 epitope of OspA and is centered around OspB Lys-253, a residue essential for H6831 recognition. A β-sheet present in the free OspB fragment is either disordered or removed by proteolysis in the H6831-bound complex. Other conformational changes between free and H6831-bound structures are minor and appear to be related to this loss. In both crystal structures, OspB C-terminal fragments form artificial dimers connected by intermolecular β-sheets. OspB structure, stability, and possible mechanisms of killing by H6831 and other bactericidal Fabs are discussed in light of the structural data.

Original languageEnglish (US)
Pages (from-to)17363-17370
Number of pages8
JournalJournal of Biological Chemistry
Issue number17
StatePublished - Apr 29 2005

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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