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

• Autor(a) principal: Taleb, Víctor
• Data de Publicação: 2022
• Outros Autores: Liao, Qinghua, Narimatsu, Yoshiki, García-García, Ana, Compañón, Ismael, Borges, Rafael Junqueira [UNESP], González-Ramírez, Andrés Manuel, Corzana, Francisco, Clausen, Henrik, Rovira, Carme, Hurtado-Guerrero, Ramon
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://dx.doi.org/10.1038/s41467-022-32021-9; http://hdl.handle.net/11449/240538

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 (Galβ1-3GalNAcα1-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 (GalNAcα1-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-π 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.