title: Crystal structure of mouse thymidylate synthase in tertiary complex with dUMP and raltitrexed reveals N-terminus architecture and two different active site conformations.
abstract: The crystal structure of mouse thymidylate synthase (mTS) in complex with substrate dUMP and antifolate inhibitor Raltitrexed is reported. The structure reveals, for the first time in the group of mammalian TS structures, a well-ordered segment of 13 N-terminal amino acids, whose ordered conformation is stabilized due to specific crystal packing. The structure consists of two homodimers, differing in conformation, one being more closed (dimer AB) and thus supporting tighter binding of ligands, and the other being more open (dimer CD) and thus allowing weaker binding of ligands. This difference indicates an asymmetrical effect of the binding of Raltitrexed to two independent mTS molecules. Conformational changes leading to a ligand-induced closing of the active site cleft are observed by comparing the crystal structures of mTS in three different states along the catalytic pathway: ligand-free, dUMP-bound, and dUMP- and Raltitrexed-bound. Possible interaction routes between hydrophobic residues of the mTS protein N-terminal segment and the active site are also discussed.
authors.affiliation: Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Dowierciał
authors.affiliation: Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland.
authors.forename: Piotr
authors.identifier: 0000-0003-2357-6216
authors.initials: P
authors.lastname: Wilk
authors.affiliation: Institute of Bioorganic Chemistry, Polish Academy of Sciences, 12/14 Noskowskiego Street, 61-704 Poznań, Poland.
authors.forename: Wojciech
authors.initials: W
authors.lastname: Rypniewski
authors.affiliation: Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland.
authors.forename: Wojciech
authors.initials: W
authors.lastname: Rode
authors.affiliation: Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland.
authors.forename: Adam
authors.initials: A
authors.lastname: Jarmuła
mesh_terms: D000818:Animals; D001665:Binding Sites; D002384:Catalysis; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D003856:Deoxyuracil Nucleotides / Q000737:chemistry*; D008024:Ligands; D051379:Mice; D008958:Models, Molecular; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D013940:Thymidylate Synthase / Q000737:chemistry*
chemical_list: D003856:Deoxyuracil Nucleotides; D008024:Ligands; C007267:2'-deoxyuridylic acid; D013940:Thymidylate Synthase