title: Structural studies of thiamin monophosphate kinase in complex with substrates and products.
abstract: Thiamin monophosphate kinase (ThiL) catalyzes the ATP-dependent phosphorylation of thiamin monophosphate (TMP) to form thiamin pyrophosphate (TPP), the active form of vitamin B 1. ThiL is a member of a small ATP binding superfamily that also includes the purine biosynthetic enzymes, PurM and PurL, NiFe hydrogenase maturation protein, HypE, and selenophosphate synthase, SelD. The latter four enzymes are believed to utilize phosphorylated intermediates during catalysis. To understand the mechanism of ThiL and its relationship to the other superfamily members, we determined the structure of Aquifex aeolicus ThiL (AaThiL) with nonhydrolyzable AMP-PCP and TMP, and also with the products of the reaction, ADP and TPP. The results suggest that AaThiL utilizes a direct, inline transfer of the gamma-phosphate of ATP to TMP rather than a phosphorylated enzyme intermediate. The structure of ThiL is compared to those of PurM, PurL, and HypE, and the ATP binding site is compared to that of PurL, for which nucleotide complexes are available.
authors.affiliation: Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA.
authors.forename: Kathryn M
authors.initials: KM
authors.lastname: McCulloch
authors.forename: Cynthia
authors.initials: C
authors.lastname: Kinsland
authors.forename: Tadhg P
authors.initials: TP
authors.lastname: Begley
authors.forename: Steven E
authors.initials: SE
authors.lastname: Ealick
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D001419:Bacteria / Q000201:enzymology; D001665:Binding Sites; D003460:Crystallization; D018360:Crystallography, X-Ray; D019281:Dimerization; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017856:Phosphotransferases (Phosphate Group Acceptor) / Q000737:chemistry*; D011487:Protein Conformation; D016415:Sequence Alignment
chemical_list: D000255:Adenosine Triphosphate; D017856:Phosphotransferases (Phosphate Group Acceptor); C022735:thiamin-phosphate kinase