The Crystal Structure and Activity of a Putative Trypanosomal Nucleoside Phosphorylase Reveal It to be a Homodimeric Uridine Phosphorylase
| Autor: | Wim G. J. Hol, Tracy L. Arakaki, Natascha Mueller, Christophe L. M. J. Verlinde, Jennifer A. Arif, George T. DeTitta, Wesley C. Van Voorhis, Alberto J. Napuli, Frank Zucker, Erkang Fan, Eric T. Larson, Jenni Ross, Angela Lauricella, Devaraja G. Mudeppa, Joseph R. Luft, J. Robert Gillespie, Frederick S. Buckner, Pradipsinh K. Rathod, Ethan A. Merritt |
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| Rok vydání: | 2010 |
| Předmět: |
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Molecular Purine Genes Protozoan Molecular Sequence Data Trypanosoma brucei brucei Protozoan Proteins Purine nucleoside phosphorylase Trypanosoma brucei Crystallography X-Ray Article Substrate Specificity chemistry.chemical_compound Structural Biology Catalytic Domain Nucleotide Amino Acid Sequence Protein Structure Quaternary Molecular Biology Nucleotide salvage DNA Primers chemistry.chemical_classification Uridine Phosphorylase Binding Sites Base Sequence Sequence Homology Amino Acid biology DNA Protozoan biology.organism_classification Molecular biology Recombinant Proteins Uridine chemistry Biochemistry Metals Uridine phosphorylase Pyrimidine metabolism RNA Interference Protein Multimerization |
| Zdroj: | Journal of Molecular Biology. 396:1244-1259 |
| ISSN: | 0022-2836 |
| Popis: | Purine nucleoside phosphorylases and uridine phosphorylases are closely related enzymes involved in purine and pyrimidine salvage, respectively, which catalyze the removal of the ribosyl moiety from nucleosides so that the nucleotide base may be recycled. Parasitic protozoa generally are incapable of de novo purine biosynthesis so the purine salvage pathway is of potential therapeutic interest. Information about pyrimidine biosynthesis in these organisms is much more limited. Though all seem to carry at least a subset of enzymes from each pathway, the dependency on de novo pyrimidine synthesis versus salvage varies from organism to organism and even from one growth stage to another. We have structurally and biochemically characterized a putative nucleoside phosphorylase from the pathogenic protozoan Trypanosoma brucei and find that it is a homodimeric uridine phosphorylase. This is the first characterization of a uridine phosphorylase from a trypanosomal source despite this activity being observed decades ago. Although this gene was broadly annotated as a putative nucleoside phosphorylase, it was widely inferred to be a purine nucleoside phosphorylase. Our characterization of this trypanosomal enzyme shows that it is possible to distinguish between purine and uridine phosphorylase activity at the sequence level based on the absence or presence of a characteristic uridine phosphorylase-specificity insert. We suggest that this recognizable feature may aid in proper annotation of the substrate specificity of enzymes in the nucleoside phosphorylase family. |
| Databáze: | OpenAIRE |
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