Thi20, a remarkable enzyme from Saccharomyces cerevisiae with dual thiamin biosynthetic and degradation activities
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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.
author list (cited authors)
Haas, A. L., Laun, N. P., & Begley, T. P.