Maltose O-acetyltransferase (MAT) and Galactoside O-acetyltransferase (GAT): MAT and GAT catalyze the CoA-dependent acetylation of the 6-hydroxyl group of their respective sugar substrates. MAT acetylates maltose and glucose exclusively at the C6 position of the nonreducing end glucosyl moiety. GAT specifically acetylates galactopyranosides. Furthermore, MAT shows higher affinity toward artificial substrates containing an alkyl or hydrophobic chain as well as a glucosyl unit. Active MAT and GAT are homotrimers, with each subunit consisting of an N-terminal alpha-helical region and a C-terminal left-handed parallel alpha-helix (LbH) subdomain with 6 turns, each containing three imperfect tandem repeats of a hexapeptide repeat motif (X-[STAV]-X-[LIV]-[GAED]-X).
Comment:Active galactoside acetyltransferase is trimeric, with active sites located at the interface between two LbH subunits. The trimer structure contains three active sites and each subunit contributes to two active sites via residues located on two surfaces.
Structure:1KRV; E. coli Galactoside Acetyltransferase trimer binds three CoA and substrate 4-nitrophenylgalactoside molecules; defined at 4A contacts. - View structure with Cn3D
Marchler-Bauer A et al. (2017), "CDD/SPARCLE: functional classification of proteins via subfamily domain architectures.",