Sequence of the gat operon for galactitol utilization from a wild-type strain EC3132 of Escherichia coli.

The sequence of the gat operon for galactitol (Gat) utilization from a wild-type isolate of Escherichia coli, strain EC3132, is presented. The operon comprises 7 open reading frames (ORFs) called gatYZABCDR. The genes are transcribed from a promoter located upstream of gatY. Genes gatABC encode the substrate-specific domains IIA, IIB and IIC of a galactitol-specific Enzyme II (EIIGat) of the phospho enol pyruvate-dependent carbohydrate:phosphotransferase system (PTS); gatD encodes an NAD-dependent Gat 1-phosphate dehydrogenase; and gatY an enzyme which hydrolyses tagatose 1,6-bisphosphate; gene gatZ is required in a cell to show a Gat+ phenotype, but its physiological function has not yet been identified; gatR encodes a repressor for the gat operon. All genes are highly similar to the gat genes from E. coli K-12; in this organism they map at 46.70 min of the gene map, equivalent to about 2180-2186 kbp.