title: Concerted action of two subunits of the functional dimer of Shewanella oneidensis MR-1 uridine phosphorylase derived from a comparison of the C212S mutant and the wild-type enzyme.
abstract: Uridine phosphorylase (UP; EC 2.4.2.3), a key enzyme in the pyrimidine-salvage pathway, catalyzes the reversible phosphorolysis of uridine to uracil and ribose 1-phosphate. The structure of the C212S mutant of uridine phosphorylase from the facultatively aerobic Gram-negative γ-proteobacterium Shewanella oneidensis MR-1 (SoUP) was determined at 1.68 Å resolution. A comparison of the structures of the mutant and the wild-type enzyme showed that one dimer in the mutant hexamer differs from all other dimers in the mutant and wild-type SoUP (both in the free form and in complex with uridine). The key difference is the `maximum open' state of one of the subunits comprising this dimer, which has not been observed previously for uridine phosphorylases. Some conformational features of the SoUP dimer that provide access of the substrate into the active site are revealed. The binding of the substrate was shown to require the concerted action of two subunits of the dimer. The changes in the three-dimensional structure induced by the C212S mutation account for the lower affinity of the mutant for inorganic phosphate, while the affinity for uridine remains unchanged.
authors.affiliation: Bach Institute of Biochemistry, Russian Academy of Sciences, 33 Leninskii Ave., Moscow 119071, Russian Federation.
authors.forename: T N
authors.initials: TN
authors.lastname: Safonova
authors.affiliation: Bach Institute of Biochemistry, Russian Academy of Sciences, 33 Leninskii Ave., Moscow 119071, Russian Federation.
authors.forename: N N
authors.initials: NN
authors.lastname: Mordkovich
authors.affiliation: Bach Institute of Biochemistry, Russian Academy of Sciences, 33 Leninskii Ave., Moscow 119071, Russian Federation.
authors.forename: V P
authors.initials: VP
authors.lastname: Veiko
authors.affiliation: Bach Institute of Biochemistry, Russian Academy of Sciences, 33 Leninskii Ave., Moscow 119071, Russian Federation.
authors.forename: N A
authors.initials: NA
authors.lastname: Okorokova
authors.affiliation: Scientific Research Institute of Physical-Chemical Medicine, Federal Medical-Biological Agency, 1a Malaya Pirogovskaya St., Moscow 119435, Russian Federation.
authors.forename: V A
authors.initials: VA
authors.lastname: Manuvera
authors.affiliation: National Research Centre `Kurchatov Institute', 1 Pl. Akademika Kurchatova, Moscow 123182, Russian Federation.
authors.forename: P V
authors.initials: PV
authors.lastname: Dorovatovskii
authors.affiliation: Bach Institute of Biochemistry, Russian Academy of Sciences, 33 Leninskii Ave., Moscow 119071, Russian Federation.
authors.forename: V O
authors.initials: VO
authors.lastname: Popov
authors.affiliation: Bach Institute of Biochemistry, Russian Academy of Sciences, 33 Leninskii Ave., Moscow 119071, Russian Federation.
authors.forename: K M
authors.initials: KM
authors.lastname: Polyakov
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D007700:Kinetics; D008958:Models, Molecular; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D020592:Shewanella / Q000201:enzymology*; D013379:Substrate Specificity; D014529:Uridine / Q000737:chemistry; D014543:Uridine Phosphorylase / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D014543:Uridine Phosphorylase; D014529:Uridine
keywords: C212S mutant; Shewanella oneidensis MR-1; substrate binding through concerted action of two subunits; uridine phosphorylase