Properties and heterologous expression of the glucose transporter GHT1 from Schizosaccharomyces pombe

Genomic DNA of the Schizosaccharomyces pombe glucose transporter, GHT1, was obtained by complementation of the glucose transport deficient St. pombe strain YCS-5. Here we describe the GHT1 gene that encodes a protein of 565 amino acids with a corresponding molecular mass of 62.5 kDa. This eukaryotic glucose transporter contains 12 putative transmembrane segments and is homologous to the HXT multigene family of S cerevisiae with several amino acid motifs of this sugar transporter family. It is also homologous to other sugar carriers from human, mouse and Escherichia coli. The function of the Ght1 protein as a glucose transporter was proved both by homologous and heterologous expression in the Sz. pombe mutant YGS-5 and in the S. cerevisiae hxt mutant RE700A, respectively. Both transformed yeast strains transported D-glucose with substrate specificity similar to that in St. pombe wild-type cells. Moreover, the cells of the two transformed yeast strains accumulated l-deoxy-D-glucose, a non-metabolizable D-glucose analogue, with an efficiency similar to Si. pombe wild-type cells. The ability of the S. cerevisiae mutant RE700A to accumulate 2DG in an Delta mu(H+) dependent manner after transformation with GHT1 provides evidence that the St. pombe transporter catalyses an energy-dependent uptake of glucose. The sequence of GHT1 was deposited at EMBL, Outstation EBI, Accession Number X91218. (C) 1997 by John Wiley & Sons, Ltd.