title: Functional evidence for active site location of tetrameric thymidylate synthase X at the interphase of three monomers.
abstract: Little is known about the catalytic mechanism of the recently discovered ThyX family of flavin-dependent thymidylate synthases that are required for thymidylate (deoxythymidine 5'-monophosphate) synthesis in a large number of microbial species. Using a combination of site-directed mutagenesis and biochemical measurements, we have identified several residues of the Helicobacter pylori ThyX protein with crucial roles in ThyX catalysis. By providing functional evidence that the active site(s) of homotetrameric ThyX proteins is formed by three different subunits, our findings suggest that ThyX proteins have evolved through multimerization of inactive monomers. Moreover, because the active-site configurations of ThyX proteins, present in many human pathogenic bacteria, and of human thymidylate synthase ThyA are different, our results will aid in the identification of compounds specifically inhibiting microbial growth.
authors.affiliation: Université Paris-Sud, Institut de Génétique et Microbiologie, Centre National de la Recherche Scientifique Unité Mixte de Recherche 8621, F-91405 Orsay Cedex, France.
authors.forename: Damien
authors.initials: D
authors.lastname: Leduc
authors.forename: Sébastien
authors.initials: S
authors.lastname: Graziani
authors.forename: Gerard
authors.initials: G
authors.lastname: Lipowski
authors.forename: Christophe
authors.initials: C
authors.lastname: Marchand
authors.forename: Pierre
authors.initials: P
authors.lastname: Le Maréchal
authors.forename: Ursula
authors.initials: U
authors.lastname: Liebl
authors.forename: Hannu
authors.initials: H
authors.lastname: Myllykallio
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D016480:Helicobacter pylori / Q000201:enzymology; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D017386:Sequence Homology, Amino Acid; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013940:Thymidylate Synthase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D013940:Thymidylate Synthase