title: Structural and thermodynamic insights into the binding mode of five novel inhibitors of lumazine synthase from Mycobacterium tuberculosis.
abstract: Recently published genomic investigations of the human pathogen Mycobacterium tuberculosis have revealed that genes coding the proteins involved in riboflavin biosynthesis are essential for the growth of the organism. Because the enzymes involved in cofactor biosynthesis pathways are not present in humans, they appear to be promising candidates for the development of therapeutic drugs. The substituted purinetrione compounds have demonstrated high affinity and specificity to lumazine synthase, which catalyzes the penultimate step of riboflavin biosynthesis in bacteria and plants. The structure of M. tuberculosis lumazine synthase in complex with five different inhibitor compounds is presented, together with studies of the binding reactions by isothermal titration calorimetry. The inhibitors showed the association constants in the micromolar range. The analysis of the structures demonstrated the specific features of the binding of different inhibitors. The comparison of the structures and binding modes of five different inhibitors allows us to propose the ribitylpurinetrione compounds with C4-C5 alkylphosphate chains as most promising leads for further development of therapeutic drugs against M. tuberculosis.
authors.affiliation: Karolinska Institutet, NOVUM, Centre for Structural Biochemistry, Huddinge, Sweden. katja.morgunova@biosci.ki.se
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Morgunova
authors.forename: Boris
authors.initials: B
authors.lastname: Illarionov
authors.forename: Thota
authors.initials: T
authors.lastname: Sambaiah
authors.forename: Ilka
authors.initials: I
authors.lastname: Haase
authors.forename: Adelbert
authors.initials: A
authors.lastname: Bacher
authors.forename: Mark
authors.initials: M
authors.lastname: Cushman
authors.forename: Markus
authors.initials: M
authors.lastname: Fischer
authors.forename: Rudolf
authors.initials: R
authors.lastname: Ladenstein
mesh_terms: D001665:Binding Sites; D001667:Binding, Competitive; D002151:Calorimetry; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000378:metabolism; D009169:Mycobacterium tuberculosis / Q000201:enzymology*; D010755:Organophosphates / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D011485:Protein Binding; D012255:Ribitol / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D013816:Thermodynamics; D014498:Uracil / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology
chemical_list: C515409:(4-(6-chloro-2,4-dioxo-1,2,3,4-tetrahydropyrimidin-5-yl)butyl) 1-phosphate; D009097:Multienzyme Complexes; D010755:Organophosphates; D012255:Ribitol; D014498:Uracil; C044822:6,7-dimethyl-8-ribityllumazine synthase