Granulicella tundricola hydroxynitrile lyase (GtHNL) and related proteins, cupin domain
This family includes archaeal, eukaryotic, and bacterial proteins homologous to hydroxynitrile lyase from Granulicella tundricola (GtHNL), a novel class of HNLs that does not show any sequence or structural similarity to any other HNL and does not contain conserved motifs typical of HNLs. HNLs comprise a diverse group of enzymes that vary in terms of their substrate specificity, enantioselectivity and the need for a co-factor. In plants, they catalyze the reversible cleavage of cyanohydrins, yielding HCN and aldehydes or ketones. Also included in this family is TM1010 from Thermotoga maritima, a protein of unknown function. Some but not all members of this family have N- or C-terminal carboxymuconolactone decarboxylase domains in addition to the cupin domain. Members of this family belong to the cupin superfamily with a conserved "jelly roll-like" beta-barrel fold capable of homodimerization.
Feature 1: metal binding site [ion binding site], 4 residue positions
Conserved feature residue pattern:H [NH] [QHE] H
Evidence:
Comment:The four-coordinate metallocenter usually includes three histidines and one glutamate; however, proteins in this subfamily may bind metal via different amino acids.
Jiyao W et al.(2023). "The conserved domain database in 2023.",