SEQUENCE OF A MELIBIOSE TRANSPORTER GENE OF ENTEROBACTER-CLOACAE

We cloned a fragment of the chromosomai DNA of Enterobacter cloacae, w hich enabled a melibiose-negative Escherichia coli mutant lacking melB to grow on melibiose as the sole source of carbon, Transformed cells harboring the hybrid plasmid carrying the cloned DNA showed melibiose transport activity. The nucleotide sequence of the DNA region was dete rmined. One complete open reading frame (ORF) and a part of another OR F were found in the region, and the amino acid sequences were deduced. The complete ORF was found to encode a melibiose transporter which co nsisted of 425 amino acid residues. Hydropathy analysis revealed that there are about 12 hydrophobic domains in this transporter. The incomp lete ORF which exists in the upstream region of the transporter gene s eemed to encode an cr-galactosidase. (C) 1997 Elsevier Science B.V.