SEQUENCE OF A NA+ GLUCOSE SYMPORTER GENE AND ITS FLANKING REGIONS OF VIBRIO-PARAHAEMOLYTICUS/

The nucleotide sequence of an approximately 6 kbp segment of chromosom al DNA of Vibrio parahaemolyticus was determined. The nucleotide seque nce revealed four open reading frames (ORFs) in this region. Hydropath y profiles of the deduced amino acid sequence of the ORFs indicate tha t ORF1 encodes a hydrophobic polypeptide with typical characteristics of a membrane transport protein. An other ORFs encode hydrophilic poly peptides. ORF1 showed significant amino acid sequence similarity to pr oteins of the SGLT (Na+/glucose symporter) family, and the amino acid sequence of ORF4 showed very high similarity to several bacterial tran scriptional repressor proteins (GalR-LacI family). We observed elevate d glucose transport activity in cells harboring a plasmid carrying the DNA region corresponding to ORF1, and the glucose transport was great ly stimulated by Na+. Thus, we believe that ORF1 encodes a Na+/glucose symporter.