title: Crystal structure of a flavin-dependent thymidylate synthase from Helicobacter pylori strain 26695.
abstract: ThyX, a flavin-dependent thymidylate synthase that is involved in the synthesis of dTMP from dUMP, is a promising target for the development of novel antibacterial drugs that aimed at blocking the biosynthesis of dTMP, one of the building blocks of DNA. This enzyme has been recently identified in some dsDNA viruses and pathogenic bacteria, including the gastric pathogen Helicobacter pylori. It shares neither sequence nor structural homology with the classical ThyA in humans and other organisms. Further more, ThyX and ThyA are the only source of dTMP in these organisms and other pathways cannot substitute for their function. Thus, ThyX-specific inhibitors could be effective antibacterial reagents while having no impact on human cells. Here we report the crystal structure of ThyX from Helicobacter pylori strain 26695 in complex with co-factor FAD and substrate dUMP at 2.5 A resolution, which consists of a 1.5 tetramer of ThyX with a total of 1248 residues, six FAD and six dUMP molecules in an asymmetric unit. The structure revealed the key residues that are involved in co-factor FAD and substrate dUMP binding, site-directed mutagenesis were performed to analysis the importance of these residues on ThyX activity by genetic complementation and FAD binding assay.
authors.affiliation: Department of Microbiology and Immunology, College of Medical Laboratory, Third Military Medical University, Chongqing 400038, People’s Republic of China.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Zhang
authors.forename: Jinyong
authors.initials: J
authors.lastname: Zhang
authors.forename: Gang
authors.initials: G
authors.lastname: Guo
authors.forename: Xuhu
authors.initials: X
authors.lastname: Mao
authors.forename: Yonglin
authors.initials: Y
authors.lastname: Hu
authors.forename: Quanming
authors.initials: Q
authors.lastname: Zou
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D003856:Deoxyuracil Nucleotides / Q000737:chemistry / Q000378:metabolism; D005182:Flavin-Adenine Dinucleotide / Q000737:chemistry / Q000378:metabolism; D005816:Genetic Complementation Test; D016480:Helicobacter pylori / Q000201:enzymology* / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D016415:Sequence Alignment; D013940:Thymidylate Synthase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D003856:Deoxyuracil Nucleotides; D005182:Flavin-Adenine Dinucleotide; C007267:2'-deoxyuridylic acid; D013940:Thymidylate Synthase