This domain family is found in bacteria, archaea and eukaryotes, and is approximately 50 amino acids in length. The family is found in association with Bacterial transferase hexapeptide (PFAM PF00132). Mac uses acetyl-CoA as acetyl donor to acetylated cytoplasmic maltose.
This entry represents a domain found in maltose acetyltransferase, which is an enzyme uses acetyl-CoA as acetyl donor to acetylate cytoplasmic maltose [ (PUBMED:1856235) ].
Maltose transacetylase of Escherichia coli. Mapping and cloning of itsstructural, gene, mac, and characterization of the enzyme as a dimer of identicalpolypeptides with a molecular weight of 20,000.
J Biol Chem. 1991; 266: 14113-8
Display abstract
malQ mutants, lacking amylomaltase, cannot grown on maltose. However, whenmaltose is present in the medium, it can be accumulated to high internal levels. In a subsequent slow reaction, accumulated maltose becomes acetylated and leaksback into the medium. The enzyme responsible for this acetylation uses acetyl-CoAas acetyl donor and can be measured in crude extracts (Boos, W., Ferenci, T., andShuman, H. A. (1981) J. Bacteriol. 146, 725-732). The structural gene for theenzyme, which we named mac, was mapped at 10.4 min on the Escherichia colilinkage map. We cloned a 3.4-kilobase pair PstI-EcoRI DNA fragment containing themac gene. Cell-free extracts of a strain harboring the multicopy plasmid wereused to purify the maltose-transacetylating activity to apparent homogeneity. On sodium dodecyl sulfate-polyacrylamide gels the enzyme exhibited a molecularweight of 20,000. Using molecular sieve chromatography, a molecular weight of40,000 was determined for the native enzyme. Therefore, the enzyme is a dimer of two identical subunits. At a sugar concentration of 100 mM the enzyme acetylates glucose, maltose, mannose, galactose, and fructose in decreasing relative rate of1, 0.55, 0.20, 0.07, 0.04. Maltotriose and other oligosaccharides were acetylatedwith 2% of the rate determined for glucose. The Km for glucose and maltose were62 and 90 mM, and the Vmax was 0.20 and 0.11 mmol/min x mg enzyme, respectively.
