Histidine hydrogen bonding in MHC at pH 5 and pH 7 modeled by molecular docking and molecular dynamics simulations

Atanas Patronov, Edvokiya Salamanova, Ivan Dimitrov, Darren R. Flower, Irini Doytchinova*

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

Hydrogen bonds play important roles in maintaining the structure of proteins and in the formation of most biomolecular protein-ligand complexes. All amino acids can act as hydrogen bond donors and acceptors. Among amino acids, Histidine is unique, as it can exist in neutral or positively charged forms within the physiological pH range of 5.0 to 7.0. Histidine can thus interact with other aromatic residues as well as forming hydrogen bonds with polar and charged residues. The ability of His to exchange a proton lies at the heart of many important functional biomolecular interactions, including immunological ones. By using molecular docking and molecular dynamics simulation, we examine the influence of His protonation/deprotonation on peptide binding affinity to MHC class II proteins from locus HLA-DP. Peptide-MHC interaction underlies the adaptive cellular immune response, upon which the next generation of commercially-important vaccines will depend. Consistent with experiment, we find that peptides containing protonated His residues bind better to HLA-DP proteins than those with unprotonated His. Enhanced binding at pH 5.0 is due, in part, to additional hydrogen bonds formed between peptide His+ and DP proteins. In acidic endosomes, protein His79β is predominantly protonated. As a result, the peptide binding cleft narrows in the vicinity of His79β, which stabilizes the peptide - HLA-DP protein complex.

Original languageEnglish
Pages (from-to)41-49
Number of pages9
JournalCurrent Computer-Aided Drug design
Volume10
Issue number1
DOIs
Publication statusPublished - 31 Dec 2014

Keywords

  • HLA-DP proteins
  • MHC class II proteins
  • molecular docking
  • molecular dynamics simulations
  • peptide
  • HLA complex

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