Two redundant genes, THI20 and THI21, of Saccharomyces cerevisiae encode a 2-methyl-4-amino-5-hydroxymethylpyrimidine monophosphate (HMP-P) kinase required for thiamin biosynthesis. Using functional complementation analysis with an Escherichia coli mutant strain and a defined biochemical system containing partially purified proteins for the reconstitution of thiamin monophosphate synthesis, we demonstrate that both Thi20p and Thi21p proteins also have HMP kinase activity. Although each isoform independently can synthesize HMP pyrophosphate (HMP-PP) from HMP, there is a marked difference in efficiency between the two proteins. The thi20 deletion strain grows at the same rate as the parental strain in minimal medium without thiamin, but its ability to synthesize HMP-PP from HMP is significantly decreased. We discuss the possibility that HMP is not involved in the pathway of de novo thiamin synthesis in S. cerevisiae.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Reference||Annotation Extension|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Conditions||Strain||Source||Reference|