Crystal structure of thiamin pyrophosphokinase

Thiamin pyrophosphate (TPP) is a coenzyme derived from vitamin B-1 (thiamin ). TTP synthesis in eukaryotes requires thiamin pyrophosphokinase (TPK), wh ich catalyzes the transfer of a pyrophosphate group from ATP to thiamin. TP P is essential for central metabolic processes, including the formation of acetyl CoA from glucose and the Krebs cycle. Deficiencies in human thiamin metabolism result in beriberi and Wernicke encephalopathy. The crystal stru cture of mouse TPK was determined by multiwavelength anomalous diffraction at 2.4 Angstrom resolution, and the structure of TPK complexed with thiamin has been refined at 1.9 Angstrom resolution. The TPK polypeptide folds as an alpha/beta -domain and a beta -sandwich domain, which share a central te n-stranded mixed beta -sheet. TPK subunits associate as a dimer, and thiami n is bound in the dimer interface. Despite lacking apparent sequence homolo gy with other proteins, the alpha/beta -domain resembles the Rossman fold a nd is similar to other kinase structures, including another pyrophosphokina se and a thiamin biosynthetic enzyme. Comparison of mouse and yeast TPK str uctures reveals differences that could be exploited in developing species-s pecific inhibitors of potential use as antimicrobial agents. (C) 2001 Acade mic Press.