Structural and functional characterization of a noncanonical nucleoside triphosphate pyrophosphatase from Thermotoga maritima
- California State University East Bay, 25800 Carlos Bee Boulevard, Hayward, CA 94542 (United States)
- Stanford Synchrotron Radiation Lightsource, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States)
A 2.15 Å resolution crystal structure of TM0159 with bound IMP and enzyme-kinetic data are presented. This noncanonical nucleoside triphosphatase from T. maritima helps to maintain a correct pool of DNA and RNA precursor molecules. The hyperthermophilic bacterium Thermotoga maritima has a noncanonical nucleoside triphosphatase that catalyzes the conversion of inosine triphosphate (ITP), deoxyinosine triphosphate (dITP) and xanthosine triphosphate (XTP) into inosine monophosphate (IMP), deoxyinosine monophosphate (IMP) and xanthosine monophosphate (XMP), respectively. The k{sub cat}/K{sub m} values determined at 323 and 353 K fall between 1.31 × 10{sup 4} and 7.80 × 10{sup 4} M{sup −1} s{sup −1}. ITP and dITP are slightly preferred over XTP. Activity towards canonical nucleoside triphosphates (ATP and GTP) was not detected. The enzyme has an absolute requirement for Mg{sup 2+} as a cofactor and has a preference for alkaline conditions. A protein X-ray structure of the enzyme with bound IMP was obtained at 2.15 Å resolution. The active site houses a well conserved network of residues that are critical for substrate recognition and catalysis. The crystal structure shows a tetramer with two possible dimer interfaces. One of these interfaces strongly resembles the dimer interface that is found in the structures of other noncanonical nucleoside pyrophosphatases from human (human ITPase) and archaea (Mj0226 and PhNTPase)
- OSTI ID:
- 22351278
- Journal Information:
- Acta Crystallographica. Section D: Biological Crystallography, Vol. 69, Issue Pt 2; Other Information: PMCID: PMC3565439; PMID: 23385455; PUBLISHER-ID: cb5016; OAI: oai:pubmedcentral.nih.gov:3565439; Copyright (c) International Union of Crystallography 2013; Country of input: International Atomic Energy Agency (IAEA); ISSN 0907-4449
- Country of Publication:
- Denmark
- Language:
- English
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