1qkz

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spinqualitylabelsall models 1qkz, resolution 1.95Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

FAB FRAGMENT (MN14C11.6) IN COMPLEX WITH A PEPTIDE ANTIGEN DERIVED FROM NEISSERIA MENINGITIDIS P1.7 SEROSUBTYPE ANTIGEN AND DOMAIN II FROM STREPTOCOCCAL PROTEIN G

Overview

Many pathogens present highly variable surface proteins to their host as a, means of evading immune responses. The structure of a peptide antigen, corresponding to the subtype P1.7 variant of the porin PorA from the human, pathogen Neisseria meningitidis was determined by solution of the X-ray, crystal structure of the ternary complex of the peptide (ANGGASGQVK) in, complex with a Fab fragment and a domain from streptococcal protein G to, 1.95 A resolution. The peptide adopted a beta-hairpin structure with a, type I beta-turn between residues Gly4P and Gly7P, the conformation of the, peptide being further stabilised by a pair of hydrogen bonds from the, side-chain of Asn2P to main-chain atoms in Val9P. The antigen binding site, within the Fab formed a distinct crevice lined by a high proportion of, apolar amino acids. Recognition was supplemented by hydrogen bonds from, heavy chain residues Thr50H, Asp95H, Leu97H and Tyr100H to main-chain and, side-chain atoms in the peptide. Complementarity-determining region (CDR), 3 of the heavy chain was responsible for approximately 50 % of the buried, surface area formed by peptide-Fab binding, with the remainder made up, from CDRs 1 and 3 of the light chain and CDRs 1 and 2 of the heavy chain., Knowledge of the structures of variable surface antigens such as PorA is, an essential prerequisite to a molecular understanding of antigenic, variation and its implications for vaccine design.

About this Structure

1QKZ is a Protein complex structure of sequences from Mus musculus, Neisseria meningitidis and Streptococcaceae. Full crystallographic information is available from OCA.

Reference

Crystal structure of an Fab fragment in complex with a meningococcal serosubtype antigen and a protein G domain., Derrick JP, Maiden MC, Feavers IM, J Mol Biol. 1999 Oct 15;293(1):81-91. PMID:10512717

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