1. Bioinformatic, Enzymatic, and Structural Characterization of Trichuris suis Hexosaminidase HEX-2.
- Author
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Dutkiewicz Z, Varrot A, Breese KJ, Stubbs KA, Nuschy L, Adduci I, Paschinger K, and Wilson IBH
- Subjects
- Animals, Substrate Specificity, Crystallography, X-Ray, Amino Acid Sequence, Phylogeny, Models, Molecular, Hexosaminidases chemistry, Hexosaminidases metabolism, Hexosaminidases genetics, Molecular Sequence Data, Catalytic Domain, Helminth Proteins chemistry, Helminth Proteins metabolism, Helminth Proteins genetics, beta-N-Acetylhexosaminidases metabolism, beta-N-Acetylhexosaminidases chemistry, beta-N-Acetylhexosaminidases genetics, Trichuris enzymology, Computational Biology methods
- Abstract
Hexosaminidases are key enzymes in glycoconjugate metabolism and occur in all kingdoms of life. Here, we have investigated the phylogeny of the GH20 glycosyl hydrolase family in nematodes and identified a β-hexosaminidase subclade present only in the Dorylaimia. We have expressed one of these, HEX-2 from Trichuris suis , a porcine parasite, and shown that it prefers an aryl β- N -acetylgalactosaminide in vitro . HEX-2 has an almost neutral pH optimum and is best inhibited by GalNAc-isofagomine. Toward N-glycan substrates, it displays a preference for the removal of GalNAc residues from LacdiNAc motifs as well as the GlcNAc attached to the α1,3-linked core mannose. Therefore, it has a broader specificity than insect fused lobe (FDL) hexosaminidases but one narrower than distant homologues from plants. Its X-ray crystal structure, the first of any subfamily 1 GH20 hexosaminidase to be determined, is closest to Streptococcus pneumoniae GH20C and the active site is predicted to be compatible with accommodating both GalNAc and GlcNAc. The new structure extends our knowledge about this large enzyme family, particularly as T. suis HEX-2 also possesses the key glutamate residue found in human hexosaminidases of either GH20 subfamily, including HEXD whose biological function remains elusive.
- Published
- 2024
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