UDP Glucose Pyrophosphorylase 1 (UGP1)

UGP1 locus in a diploid strain, followed by tetrad analysis, showed that UGPase is essential for cell viability. Functional analysis of UGP1 was carried out by generating strains in which UGPase could be either overexpressed or depleted. This was done by generating haploid strains carrying either UGP1 on a multicopy vector or the chromosomal deletion of UGP1, and rescued by a vector bearing the wild-type gene under the control of the glucose-repressible galactose-inducible promoter. The effects of overproducing UGPase on the cell metabolism and morphology were carbon-source dependent. In contrast, on galactose, the 40-fold increase in UGPase activity was accompanied by several effects, including a threefold reduction of the growth rate, a 3-5-fold increase in the concentrations of UDP-Glc, UDP-Gal and galactose 1-phosphate, a higher sensitivity to calcofluor white and an increase in the degree of protein glycosylation.