Disease relevance of PSA1

• We demonstrated the enzyme activity of Vig9 protein using a recombinant fusion protein produced in Escherichia coli [1].
• Although the null mutant was lethal, the vig9 mutants so far obtained showed no growth defect but immature protein glycosylation and drug hypersensitivity [2].

High impact information on PSA1

• A disruption mutant created by the insertion of a TRP1 marker into SRB1 displayed only the lysis ability phenotype and was not dependent on an osmotic stabilizer for growth [3].
• The integrated marker was used to map SRB1 to chromosome XV by Southern hybridization and pulsed-field gel electrophoresis [3].
• Saccharomyces cerevisiae VIG9 encodes GDP-mannose pyrophosphorylase, which is essential for protein glycosylation [1].
• We examined the enzyme activity to synthesize GDP-mannose in the cell extracts of the wild type, vig9-1 mutant, and VIG9 transformant yeasts [1].
• The genes encoding GDP-mannose pyrophosphorylase from Saccharomyces cerevisiae (SRB1/PSA1) and Candida albicans (CaSRB1) were expressed under the control of the tightly regulated promoters of MET3 and CaMET3 respectively [4].

Chemical compound and disease context of PSA1

• We examined the enzyme activity of a glutathione S-transferase fusion of each VIG9 gene to synthesize GDP mannose in the cell extracts of a heterologous Escherichia coli expression system [5].

Biological context of PSA1

• Pathway activation was also suppressed in dpm1-101 mutants by plasmids that contained RER2 or PSA1, which produce the substrates for Dpm1 [6].
• Isolation of a Trichoderma reesei cDNA encoding GTP: a-D-mannose-1-phosphate guanyltransferase involved in early steps of protein glycosylation [7].
• A cDNA coding for GTP: alpha-d-mannose-1-phosphate guanyltransferase (MPG1 transferase) (EC 2.7.7.13) was isolated from a cDNA library of the Trichoderma reesei RutC-30 strain by suppression of the yeast Saccharomyces cerevisiae mutation in the DPM1gene encoding mannosylphosphodolichol (MPD) synthase [7].
• In addition, the new pattern of expression of SRB1/PSA1 resulted in a dominant flocculation phenotype at all phases of batch growth [8].
• PSA1 is an essential gene, and PSA1 transcription is nearly co-ordinately regulated with CLN2 transcription, peaking near START [9].

Anatomical context of PSA1

• These results suggest that greater exposure of flocculin on the cell surface, caused by either cell wall distortion (through depletion of Pkc1p) or aberrant regulation of mannosylation (through constitutive production of Srb1p), results in an increased flocculation ability [8].

Associations of PSA1 with chemical compounds

• Methionine-mediated repression of either PSA1/SRB1 or PKC1 resulted in enhanced cell clumping [8].
• A previously reported complementing gene, which this study has now identified as PDE2, is a multi-copy suppressor of sorbitol dependence and is not, as was previously suggested, the SRB1 gene. srb and pde2 mutants share a number of phenotypes, including lysis upon hypotonic shock and enhanced transformability [10].
• Combined genetic and biochemical analysis shows that the srb1 mutation is responsible for the reduction of alkali-soluble glucan [11].
• GDP-mannose pyrophosphorylase and L-galactono-1,4-lactone dehydrogenase have been cloned [12].

Other interactions of PSA1

• In the alg1 and alg2 mutants, complemented with MPG1 gene, N-glycosylation of invertase was in part restored, to a degree comparable to that of the wild-type control [13].
• A plasmid suppressor of alg1, PSA1, encodes a 361 amino-acid protein with homology to NDP-hexose pyrophosphorylases, the enzymes that catalyze the formation of activated sugar nucleotides [9].
• The autonomously replicating plasmid YEpSS1, containing the S. cerevisiae SOD1 and SRB1 genes, was highly unstable in a wild-type strain [14].

References