The Catalytic Acid-Base in GH109 Resides in a Conserved GGHGG Loop and Allows for Comparable α-Retaining and β-Inverting Activity in an N-Acetylgalactosaminidase from Akkermansia muciniphila

• Enzymes active on glycosidic bonds are defined according to the stereochemistry of both substrates and products of the reactions they catalyze. The CAZy classification further assigns these enzymes into sequence-based families sharing a common stereochemistry for substrates (either α- or β-) and products (i.e., inverting or retaining mechanism). Here we describe the N-acetylgalactosaminidases AmGH109A and AmGH109B (i.e., GH109: glycoside hydrolase family 109) from the human gut symbiont Akkermansia muciniphila. Notably, AmGH109A displays α-retaining and β-inverting N-acetylgalactosaminidase activities with comparable efficiencies on natural disaccharides. This dual specificity could provide an advantage in targeting a broader range of host-derived glycans. We rationalize this discovery through bioinformatics, structural, mutational, and computational studies, unveiling a histidine residing in a conserved GGHGG motif as the elusive catalytic acid-base of the GH109 family.

Subject headings

TEKNIK OCH TEKNOLOGIER  -- Industriell bioteknik -- Biokatalys och enzymteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Industrial Biotechnology -- Biocatalysis and Enzyme Technology (hsv//eng)

Keyword

GH4

glycoside hydrolase

human gut microbiota

inverting

MD simulations

mechanism

mucin

retaining

Publication and Content Type

art (subject category)

ref (subject category)