User:Marvin O'Neal/Antibody OspA and OspB
From Proteopedia
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Introduction
The causative agent of disease is Borellia burgdorferi, a spirochaete found in the gut of hard bodied ticks of genus Ixodes. A factor contributing to the severity of Lyme disease is its resistance to complement-dependent lysis. Lysis in the absence of complement is necessary to clear Borrelia burgdorferi. Certain Fragment Antigen Binding (fab) fragments of antibody are bactericidal even in the absence of a complement. The binding of specific fabs of IgG and IgM monoclonal antibodies to OspA and OspB of the Borrelia leads to a complement-independent lysis of the bacteria [1].
Interaction With OspB
1FJ1- OspB + H6831
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IgG antibody fabs CB2 and H6831 are structurally similar and both target the C-terminal of OspB. ##H6831 consists of a heavy and a light chain and each chain is composed of a variable and a constant domain.## The paratope is located at the N terminal of the variable region of both the heavy and the light chains (Putnam 1979). Fab binding destabilizes the outer membrane (OM) of B. burdorferi with subsequent formation of spheroplasts. It has been observed that the bactericidal action, but not the binding, requires the presence of bivalent cations (Mg2+ and Ca2+). Escudero et al. study demonstrated the inability of fab to kill bacteria in the absence of the bivalent cations. It was speculated that OspB- Cb2 (a fab similar to H6831) complexes could create physical openings in the OM allowing for rapid infusion of electrolytes, increasing the osmolarity of the periplasm and triggering bivalent cation dependent cascades (Escudero; Halluska et al. 1997)
Lys-253
doing its thing.
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Homologous Structures in OspA=
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