title: Thi20, a remarkable enzyme from Saccharomyces cerevisiae with dual thiamin biosynthetic and degradation activities.
abstract: Saccharomyces cerevisiae Thi20 is a fusion protein with homology to Bacillus subtilis ThiD and TenA. The N-terminus of Thi20 has significant sequence homology to B. subtilis ThiD, while the C-terminus has homology to B. subtilis TenA. Incubation of Thi20 with thiamin reveals that it has thiaminase II activity, in addition, incubation of Thi20 with HMP (4-amino-2-methyl-5-hydroxymethylpyrimidine) and ATP reveals that it has HMP kinase and HMP-P (4-amino-2-methyl-5-hydroxymethylpyrimidine phosphate) kinase activity. This demonstrates that Thi20 is a trifunctional protein with thiamin biosynthetic and degradative activity.
authors.affiliation: Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Amy L
authors.initials: AL
authors.lastname: Haas
authors.forename: Nathan P
authors.initials: NP
authors.lastname: Laun
authors.forename: Tadhg P
authors.initials: TP
authors.lastname: Begley
mesh_terms: D000595:Amino Acid Sequence; D002384:Catalysis; D002851:Chromatography, High Pressure Liquid; D006867:Hydrolases / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D010770:Phosphotransferases / Q000378:metabolism; D011743:Pyrimidines / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D016415:Sequence Alignment; D013831:Thiamine / Q000096:biosynthesis / Q000378:metabolism*
chemical_list: D011743:Pyrimidines; D010770:Phosphotransferases; D006867:Hydrolases; C022731:thiaminase II; C012068:toxopyrimidine; D013831:Thiamine