Galactoside acetyltransferase



Galactoside acetyltransferase (also known as Galactoside O-acetyltransferase, thiogalactoside transacetylase, β-galactoside transacetylase and GAT) is an enzyme that transfers an acetyl group from acetyl-CoA to β-galactosides, glucosides and lactosides. It is coded for by the lacA gene of the lac operon in E. coli.

Reaction
It catalyzes the following reaction:

acetyl-CoA + beta-D-galactoside → CoA + 6-acetyl-beta-D-galactoside

The kinetics of the enzyme were delineated in 1995.

Biological role
The enzyme's role in the classical E.coli lac operon remains unclear. However, the enzyme's cellular role may be to detoxify non-metabolizable pyranosides by acetylating them and preventing their reentry into the cell.