# Unravelling the Glycan Code: Molecular Dynamics and Quantum Chemistry Reveal How O‐Glycan Functional Groups Govern OgpA Selectivity in Mucin Degradation by Akkermansia muciniphila

## TL;DR

This study explores how the OgpA enzyme from Akkermansia muciniphila selectively degrades mucin glycans using molecular dynamics and quantum chemistry.

## Contribution

The study reveals how O-glycan functional groups govern OgpA selectivity through molecular interactions and electrophilic character.

## Key findings

- Peptide binding to OgpA involves hydrogen bonds, π–π interactions, van der Waals forces, and electrostatic interactions.
- The enzyme's selectivity is primarily determined by the interaction between the peptide's functional group and the binding cavity.
- OgpA prefers peptides with lower electrophilic character, as shown by quantum chemistry calculations.

## Abstract

Mucins, heavily O‐glycosylated glycoproteins, are a key component of mucus, and certain gut microbiota, including
Akkermansia muciniphila
, can utilise mucin glycans as a carbon source.
Akkermansia muciniphila
produces the O‐glycopeptidase enzyme OgpA, which cleaves peptide bonds at the N‐terminus of serine (Ser) or threonine (Thr) residues carrying O‐glycan substitutions, with selectivity influenced by the O‐glycan functional groups. Using molecular dynamics (MD) simulations and quantum chemistry calculations, we explored how different O‐glycan groups affect OgpA's selectivity. Our results show that peptides bind to the enzyme via hydrogen bonds, π–π interactions, van der Waals forces and electrostatic interactions, with key residues, including Tyr90, Val138, Gly176, Tyr210 and Glu91, playing important roles. The primary determinant of selectivity is the interaction between the peptide's functional group and the enzyme's binding cavity, while peptide–enzyme interface interactions are secondary. Quantum chemistry calculations reveal that OgpA prefers peptides with a lower electrophilic character. This study provides new insights into mucin degradation by gut microbiota enzymes, advancing our understanding of this critical biological process.