Carregant...
Fitxers
Tipus de document
ArticleVersió
Versió acceptadaData de publicació
Llicència de publicació
Si us plau utilitzeu sempre aquest identificador per citar o enllaçar aquest document: https://hdl.handle.net/2445/222480
An Unusual His/Asp Dyad Operates Catalysis in Agar-Degrading Glycosidases
Títol de la revista
Director/Tutor
ISSN de la revista
Títol del volum
Recurs relacionat
Resum
Agarose motifs, found in agars present in the cell walls of red algae, consist of alternating units of d-galactose (G) and α-3,6-anhydro-l-galactose (LA). Glycoside hydrolases from family 117 (GH117) cleave the terminal α-1,3-glycosidic bonds, releasing LA units. Structural studies have suggested that these enzymes use unconventional catalytic machinery, involving a histidine (His302) as a general acid rather than a carboxylic residue as in most glycosidases. By means of quantum mechanics/molecular mechanics metadynamics, we investigated the reaction mechanism of Phocaeicola plebeius GH117, confirming the catalytic role of His302. This residue shares a proton with a neighbor aspartate residue (Asp320), forming a His/Asp dyad. Our study also reveals that, even though the sugar unit at the –1 subsite (LA) can adopt two conformations, 4C1 and 1,4B, only the latter is catalytically competent, defining a 1,4B → [4E]‡ → 1,4B (→ 4C1) conformational itinerary. This mechanism may be applicable to similar enzymes with a His/Asp dyad in their active sites, such as GH3 β-N-acetylglucosaminidase and GH156 sialidase. These insights enhance our understanding of glycosidase catalytic strategies and could inform the engineering of enzymes for the more efficient processing of seaweed.
Matèries
Matèries (anglès)
Citació
Citació
SAGIROGLUGIL, Mert, NIN HILL, Alba, FICKO-BLEAN, Elizabeth, ROVIRA I VIRGILI, Carme. An Unusual His/Asp Dyad Operates Catalysis in Agar-Degrading Glycosidases. _ACS Catalysis_. 2024. Vol. 14, núm. 22, pàgs. 16897-16904. [consulta: 8 de gener de 2026]. ISSN: 2155-5435. [Disponible a: https://hdl.handle.net/2445/222480]