Structural and mechanistic insights into the cleavage of clustered O-glycan patches-containing glycoproteins by mucinases of the human gut

Author(s):Show less -

Taleb, Victor ; Liao, Qinghua ; Narimatsu, Yoshiki ; Garcia-Garcia, Ana ; Companon, Ismael ; Borges, Rafael Junqueira ; Gonzalez-Ramirez, Andres Manuel ; Corzana, Francisco ; Clausen, Henrik ; Rovira, Carme ; Hurtado-Guerrero, Ramon

• Document type: Journal article
• Source: NATURE COMMUNICATIONS; v. 13, n. 1, p. 15-pg., 2022-07-26.

Abstract

Mucinases of human gut bacteria cleave peptide bonds in mucins strictly depending on the presence of neighboring O-glycans. The Akkermansia muciniphila AM0627 mucinase cleaves specifically in between contiguous (bis) O-glycans of defined truncated structures, suggesting that this enzyme may recognize clustered O-glycan patches. Here, we report the structure and molecular mechanism of AM0627 in complex with a glycopeptide containing a bis-T (Gal beta 1-3GalNAc alpha 1-O-Ser/Thr) O-glycan, revealing that AM0627 recognizes both the sugar moieties and the peptide sequence. AM0627 exhibits preference for bis-T over bis-Tn (GalNAc alpha 1-O-Ser/Thr) O-glycopeptide substrates, with the first GalNAc residue being essential for cleavage. AM0627 follows a mechanism relying on a nucleophilic water molecule and a catalytic base Glu residue. Structural comparison among mucinases identifies a conserved Tyr engaged in sugar-pi interactions in both AM0627 and the Bacteroides thetaiotaomicron BT4244 mucinase as responsible for the common activity of these two mucinases with bis-T/Tn substrates. Our work illustrates how mucinases through tremendous flexibility adapt to the diversity in distribution and patterns of O-glycans on mucins. AM0627 is a bis-O-glycan mucinase that might work in the final steps of mucus degradation, thereby providing a carbon and nitrogen source for Akkermansia muciniphila. Here, the authors provide molecular insights into AM0627 function from X-ray crystallography and computer simulations. (AU)

• FAPESP's process: 16/24191-8 - Development of methods for crystallographic structure elucidation and structural studies of toxic mechanism of snake venom Phospholipases A2 homologue proteins
• Grantee: Rafael Junqueira Borges
• Support Opportunities: Scholarships in Brazil - Post-Doctoral