Member database | CDD |
CDD type | domain |
Short name | A4_beta-galactosidase_middle_domain |
Set | GAT_1 |
Description
A4 beta-galactosidase middle domain: a type 1 glutamine amidotransferase (GATase1)-like domain. This group includes proteins similar to beta-galactosidase from Thermus thermophilus. Beta-Galactosidase hydrolyzes the beta-1,4-D-galactosidic linkage of lactose, as well as those of related chromogens, o-nitrophenyl-beta-D-galactopyranoside (ONP-Gal) and 5-bromo-4-chloro-3-indolyl-beta-D-galactoside (X-gal). This A4 beta-galactosidase middle domain lacks the catalytic triad of typical GATase1 domains. The reactive Cys residue found in the sharp turn between a beta strand and an alpha helix termed the nucleophile elbow in typical GATase1 domains is not conserved in this group.
[1]References
1.Trimeric crystal structure of the glycoside hydrolase family 42 beta-galactosidase from Thermus thermophilus A4 and the structure of its complex with galactose. Hidaka M, Fushinobu S, Ohtsu N, Motoshima H, Matsuzawa H, Shoun H, Wakagi T. J. Mol. Biol. 322, 79-91, (2002). View articlePMID: 12215416