Applied Microbiology and Biotechnology, Vol.97, No.11, 4957-4964, 2013
ght2 (+) is required for UDP-galactose synthesis from extracellular galactose by Schizosaccharomyces pombe
Schizosaccharomyces pombe has eight hexose transporter genes, ght1 (+) to ght8 (+). Here we report that ght2 (+), which is highly expressed in the presence of glucose, is essential for UDP-galactose synthesis from extracellular galactose when cells grow on glucose. The galactosylation defect of a uge1 Delta mutant defective in synthesis of UDP-galactose from glucose was suppressed in galactose-containing medium, but disruption of ght2 (+) in the uge1 Delta mutant reversed suppression of the galactosylation defect. Expression of Saccharomyces cerevisiae GAL2 in uge1 Delta ght2 Delta cells suppressed the defective galactosylation phenotype in galactose-containing medium. These results indicate that galactose is transported from the medium to the cytosol in a Ght2-dependent manner, and is then converted into UDP-galactose.