User:Marvin O'Neal/OspC: Difference between revisions

<scene name='Studio:G4SecL04/Alpha_2_and3_and_4/1' target='1'>α4 (residues 152-159)</scene>. At the end of membrane surface, the connection between helices α1 and α2 forms two short anti-parallel β-strands,  

<scene name='Studio:G4SecL04/Beta_01/1' target='1'>β1 (residues 79-80)</scene>,and  

<scene name='Studio:G4SecL04/Beta_02/1' target='1'>β2 (residues 88-89)</scene> are formed. Based on the alignment of all oMGs, towards the membrane proximal end, the surface-exposed residues on α1 and α5 are highly conserved, resulting positively charged surface. Other than those on helices, α1 and α5, the surface-exposed residues on the remaining regions of OspC molecule are variable.

 

 

 

 

At the membrane distal region, the six loop regions, including two β-strands illustrates the most antigenic sites of OspC due to the presence of variable surface-exposed residues among OspC isolates. <ref>Earnhart C, LeBlanc D, Alix K, Desrosiers D, Radolf J, and Marconi R. 2010. Identification of residues within ligand-binding domain 1 (LBD1) of the ''Borrelia burgdorferi'' OspC protein required for function in the mammalian environment. Molecular Microbiology 76(2): 393-408. [http://dx.crossref.org/10.1111%2Fj.1365-2958.2010.07103.x DOI: 10.1111/j.1365-2958.2010.07103.x]</ref>. However, among these variable regions, the outer surface-exposed residues connecting the helices α1 and α2, forming the loops, L1 (residues 74-78), L2 (residues 81-87), L3 (residues 90-93) and two short beta strands, β1 and β2 and also L5 (residues 146-150) are more highly variable than those present in the loops, L4 (residues 115-119) and L6 (residues 161-169). Consequently, the surface potential of red region that projects away from the membrane is negatively charged and mainly involved in the protein-protein or protein-ligand interactions (Eicken et al. 2001). Only four types of oMGs (A, B, I and K), whose surface potential in red region is highly negative relative to non-invasive one plays a major role in pathogenesis of human Lyme disease (Kumaran 2001). The residue, <scene name='Studio:G4SecL04/82nd_residue/1'>His82</scene>, located on the red region at the membrane distal end is unique that the replacement of other residues except His82, Lys82, Gln82, which are present only in four invasive oMGs enhances the possibility of turning invasive strains to non-invasive one. Thus, the stronger the electrostatic potential on red region, the higher the chance for OspC to bind with positively charged host ligands. Therefore, the alternation of an amino acid residue at the 82nd position on red region not only demonstrates OspC polymorphism, but also points out the probability for turning invasive strains to non-invasive strains <ref>Kumaran D, Eswaramoorthy S, Luft B, Koide S, Dunn J, Lawson C, and Swaminathan S. 2001. Crystal Structure of Outer Surface Protein C (OspC) from the Lyme Disease Spirochete, ''Borrelia burgdorferi''. The EMBO Journal 20(5): 971-978. [http://dx.crossref.org/10.1093%2Femboj%2F20.5.971 DOI:  10.1093/emboj/20.5.971]</ref>.