Sequence of a Na+/glucose symporter gene and its flanking regions of Vibrio parahaemolyticus.

The nucleotide sequence of an approximately 6 kbp segment of chromosomal DNA of Vibrio parahaemolyticus was determined. The nucleotide sequence revealed four open reading frames (ORFs) in this region. Hydropathy profiles of the deduced amino acid sequence of the ORFs indicate that ORF1 encodes a hydrophobic polypeptide with typical characteristics of a membrane transport protein. All other ORFs encode hydrophilic polypeptides. ORF1 showed significant amino acid sequence similarity to proteins of the SGLT (Na+/glucose symporter) family, and the amino acid sequence of ORF4 showed very high similarity to several bacterial transcriptional repressor proteins (GalR-LacI family). We observed elevated glucose transport activity in cells harboring a plasmid carrying the DNA region corresponding to ORF1, and the glucose transport was greatly stimulated by Na+. Thus, we believe that ORF1 encodes a Na+/glucose symporter.