Identification of a candidate glycosaminoglycan-binding adhesin of the Lyme disease spirochete Borrelia burgdorferi

Binding of glycosaminoglycans (GAGs) by Borrelia burgdorferi, the Lyme dise ase spirochete, has the potential to promote the colonization of diverse ti ssues. GAG binding by B. burgdorferi is associated with haemagglutination a nd we have identified a 26 kDa protein, which we have termed Bgp (Borrelia GAG-binding protein), on the basis of its ability to bind to heparin and er ythrocytes. Bgp was found in outer membrane fractions of B. burgdorferi and on the surface of intact bacteria, as assayed by labelling with a membrane -impermeable biotinylating agent or anti-Bgp antibodies. Purified recombina nt Bgp agglutinated erythrocytes, binds to the same spectrum of GAGs as the B. burgdorferi strain from which the cloned bgp sequence was obtained, and inhibited B. burgdorferi binding to purified GAGs and to cultured mammalia n cells. Thus, Bgp is a strong candidate for a GAG-binding adhesin of B. bu rgdorferi.