New Insight into the Substrate Selectivity of Bovine Milk γ-glutamyl Transferase via Structural and Molecular Dynamics Predictions

Molecules. 2023 Jun 9;28(12):4657. doi: 10.3390/molecules28124657.

Abstract

Bovine milk γ-glutamyltransferase (BoGGT) can produce γ-glutamyl peptides using L-glutamine as a donor substrate, and the transpeptidase activity is highly dependent on both γ-glutamyl donors and acceptors. To explore the molecular mechanism behind the donor and acceptor substrate preferences for BoGGT, molecular docking and molecular dynamic simulations were performed with L-glutamine and L-γ-glutamyl-p-nitroanilide (γ-GpNA) as donors. Ser450 is a crucial residue for the interactions between BoGGT and donors. BoGGT forms more hydrogen bonds with L-glutamine than γ-GpNA, promoting the binding affinity between BoGGT and L-glutamine. Gly379, Ile399, and Asn400 are crucial residues for the interactions between the BoGGT intermediate and acceptors. The BoGGT intermediate forms more hydrogen bonds with Val-Gly than L-methionine and L-leucine, which can promote the transfer of the γ-glutamyl group from the intermediate to Val-Gly. This study reveals the critical residues responsible for the interactions of donors and acceptors with the BoGGT and provides a new understanding of the substrate selectivity and catalytic mechanism of GGT.

Keywords: molecular docking; molecular dynamic simulation; γ-glutamyl acceptor; γ-glutamyl donor; γ-glutamyl-enzyme intermediate.

MeSH terms

  • Animals
  • Cattle
  • Glutamine / chemistry
  • Milk Proteins* / chemistry
  • Milk* / enzymology
  • Molecular Dynamics Simulation
  • Protein Conformation
  • Protein Folding
  • Substrate Specificity
  • gamma-Glutamyltransferase* / chemistry

Substances

  • gamma-Glutamyltransferase
  • Milk Proteins
  • Glutamine

Grants and funding

This research was funded by the China Scholarship Council, grant number 201903250091, and the Novo Nordisk Foundation to the Proferment project, grant application no.—NNF21OC0066330. Data was generated though accessing research infrastructure at University of Copenhagen, including FOODHAY (Food and Health Open Innovation Laboratory, Danish Roadmap for Research Infrastructure).