G13secL03Tpc3: Difference between revisions

<Structure load='1RJL' size='500' frame='true' align='right' scene='G13secL03Tpc3/Final_ospb/1'/>

<Structure load='1RJL' size='500' frame='true' align='right' scene='G13secL03Tpc3/Final_bsheet/1'/>

The structure of Osp B shows that there are three exposed loops in which are affected by the antibody, H6831. The majority of interaction comes between the antibody’s heavy chain and loop 2 on the lipoprotein, residues 250-254. The loop forms electrostatic interaction and hydrogen bond interactions with the antibody's heavy chain. Lysine 253, which resides on loop 2 play an important role in the recognition of the antibody, thus the antibody having the most interaction with loop 2. The Lysine interacts with the antibody by forming hydrogen bonds with the glutamine and histidine on the heavy chain of H6831. <scene name='G13secL03Tpc3/Loop_1/1'>Loop 1</scene>, residues 231-233, also interacts with the Fab heavy chain forming two hydrogen bonds. Loop 3, residues 272-276, interact with the light chain, of the antibody with two hydrogen bonds. <ref name=Article2> PMID:15864264 </ref>

The more significant change that occurs from the bactericidal antibody is in the first four beta sheets. The surrounding sheets shift and overlap to replace the missing sheets. The removal of these sheets can affect the outer surface protein and make the bacteria more susceptible to lysis.  

The bacteria lyses indirectly. The proteolytic activity of the antibody on the bacteria is presumably similar to a membrane attack complex (MAC). The complement system activates the classical pathway, activating effector proteins which insert themselves in the outer membrane of the bacteria and disrupting it and causing death to the cell.  <ref name=Article3> PMID:15864264 </ref>

[[Image:Mac attack.PNG‎|thumb|400px|Mechanism of destruction by MAC on the bacteria, ''Borrelia burgdorferi'']]  

OspB is capable of existing in various forms, with a different amino acid in place of Lysine-253, responsible for recognition of the antibody. <ref name=Article4> PMID: 15128807 </ref>  Mutations occur in the residue of Lysine, which prevent it from being recognized and lysed by bactericidal Fabs such as H6381. The study of this structure of Osp B is important to combat future mechanisms of curing Lyme disease. Vaccines for Osp B have not yet been discovered due to the increased variability in the epitope, as the vaccine wouldn’t be able to counteract a wide variety of strains of “Borrelia.” However, the ability of H6381 and CB2 to make the bacteria subject to increased proteolytic activity is a possibility for future research as it is still currently misunderstood.