Biology:Polynucleotide 5'-phosphatase
| polynucleotide 5′-phosphatase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| EC number | 3.1.3.33 | ||||||||
| CAS number | 37288-17-8 | ||||||||
| Databases | |||||||||
| IntEnz | IntEnz view | ||||||||
| BRENDA | BRENDA entry | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| Gene Ontology | AmiGO / QuickGO | ||||||||
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The enzyme polynucleotide 5′-phosphatase (RNA 5′-triphosphatase, RTPase, EC 3.1.3.33) is an enzyme that catalyzes the reaction
- a 5′-phosphopolynucleotide + H2O [math]\displaystyle{ \rightleftharpoons }[/math] a polynucleotide + phosphate
This enzyme belongs to the family of hydrolases, specifically those acting on phosphoric monoester bonds. The systematic name is polynucleotide 5′-phosphohydrolase. This enzyme is also called 5′-polynucleotidase.
The only specific molecular function known is the catalysis of the reaction:
- a 5′-end triphospho-(purine-ribonucleotide) in mRNA + H2O = a 5′-end diphospho-(purine-ribonucleoside) in mRNA + phosphate
RTPases cleave the 5′-terminal γ-β phosphoanhydride bond of nascent messenger RNA molecules, enabling the addition of a five-prime cap as part of post-transcriptional modifications. RTPases generate 5′-diphosphate-ended mRNA and a phosphate ion from 5′-triphosphate-ended precursor mRNA. mRNA guanylyltransferase then adds a backwards guanosine monophosphate (GMP) group from GTP, generating pyrophosphate, and mRNA (guanine-N7-)-methyltransferase methylates the guanine to form the final 5′-cap structure.[1][2][3][4][5]
There are two families of RTPases known so far:
- the metal-dependent family. Yeast,[4][6][7] protozoan, and viral[4][8] RTPases require a metal co-factor for their activity, which is most often either Mg2+ or Mn2+. This class of enzymes is also able to hydrolyze free nucleoside triphosphates in the presence of either Mn2+ or Co2+.[1]
- the metal-independent family. These groups do not require metals for their activity, and some enzymes have been shown to be inactivated in the presence of metal ions. These enzymes are very much similar to protein tyrosine phosphatases in their structure and mechanism.[9][10][11] This family includes RTPases from mammals, plants, and other higher eukaryotes,[8] and is structurally and mechanistically different from the metal-dependent RTPase family.[4][5][7]
Structural studies
As of late 2007, 5 structures have been solved for this class of enzymes, with PDB accession codes 1D8H, 1D8I, 1I9S, 1I9T, and 1YN9.
See also
- Transcription (genetics)
- Five-prime cap
References
- ↑ 1.0 1.1 "Characterization of a baculovirus-encoded RNA 5′-triphosphatase". Journal of Virology 72 (9): 7057–63. September 1998. doi:10.1128/JVI.72.9.7057-7063.1998. PMID 9696798.
- ↑ "Genetic, physical, and functional interactions between the triphosphatase and guanylyltransferase components of the yeast mRNA capping apparatus". Molecular and Cellular Biology 18 (9): 5189–98. September 1998. doi:10.1128/MCB.18.9.5189. PMID 9710603.
- ↑ "Structure, mechanism, and evolution of the mRNA capping apparatus". Progress in Nucleic Acid Research and Molecular Biology 66: 1–40. 2000. doi:10.1016/s0079-6603(00)66025-7. ISBN 9780125400664. PMID 11051760.
- ↑ 4.0 4.1 4.2 4.3 "An RNA 5′-triphosphatase related to the protein tyrosine phosphatases". Cell 89 (6): 867–73. June 1997. doi:10.1016/S0092-8674(00)80272-X. PMID 9200605.
- ↑ 5.0 5.1 "Mammalian capping enzyme binds RNA and uses protein tyrosine phosphatase mechanism". Proceedings of the National Academy of Sciences of the United States of America 95 (21): 12226–31. October 1998. doi:10.1073/pnas.95.21.12226. PMID 9770468. Bibcode: 1998PNAS...9512226W.
- ↑ "Investigating the role of metal ions in the catalytic mechanism of the yeast RNA triphosphatase". The Journal of Biological Chemistry 278 (36): 33963–71. September 2003. doi:10.1074/jbc.M303007200. PMID 12819229.
- ↑ 7.0 7.1 "Structure and mechanism of yeast RNA triphosphatase: an essential component of the mRNA capping apparatus". Cell 99 (5): 533–43. November 1999. doi:10.1016/S0092-8674(00)81541-X. PMID 10589681.
- ↑ 8.0 8.1 "RNA 5'-triphosphatase activity of the hepatitis E virus helicase domain". Journal of Virology 84 (18): 9637–41. September 2010. doi:10.1128/JVI.00492-10. PMID 20592074.
- ↑ "Crystal structure of human protein tyrosine phosphatase 1B". Science 263 (5152): 1397–404. March 1994. doi:10.1126/science.8128219. PMID 8128219. Bibcode: 1994Sci...263.1397B.
- ↑ "Protein tyrosine phosphatases: mechanisms of catalysis and regulation". Current Opinion in Chemical Biology 2 (5): 633–41. October 1998. doi:10.1016/S1367-5931(98)80095-1. PMID 9818190.
- ↑ "Human PIR1 of the protein-tyrosine phosphatase superfamily has RNA 5'-triphosphatase and diphosphatase activities". The Journal of Biological Chemistry 274 (23): 16590–4. June 1999. doi:10.1074/jbc.274.23.16590. PMID 10347225.
Further reading
- "The enzymatic cleavage of phosphate termini from polynucleotides". The Journal of Biological Chemistry 242 (5): 936–50. March 1967. doi:10.1016/S0021-9258(18)96215-0. PMID 4289819.
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