The enzyme polynucleotide 5′-phosphatase (RNA 5′-triphosphatase, RTPase, EC 3.1.3.33) is an enzyme that catalyzes the reaction
| polynucleotide 5′-phosphatase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| EC no. | 3.1.3.33 | ||||||||
| CAS no. | 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 | ||||||||
| |||||||||
- a 5′-phosphopolynucleotide + H2O 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 edit
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 edit
References edit
- ^ a b Gross CH, Shuman S (September 1998). "Characterization of a baculovirus-encoded RNA 5′-triphosphatase". Journal of Virology. 72 (9): 7057–63. doi:10.1128/JVI.72.9.7057-7063.1998. PMC 109926. PMID 9696798.
- ^ Ho CK, Schwer B, Shuman S (September 1998). "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. doi:10.1128/MCB.18.9.5189. PMC 109104. PMID 9710603.
- ^ Shuman S (2000). "Structure, mechanism, and evolution of the mRNA capping apparatus". Progress in Nucleic Acid Research and Molecular Biology. 66: 1–40. doi:10.1016/s0079-6603(00)66025-7. ISBN 9780125400664. PMID 11051760.
- ^ a b c d Takagi T, Moore CR, Diehn F, Buratowski S (June 1997). "An RNA 5′-triphosphatase related to the protein tyrosine phosphatases". Cell. 89 (6): 867–73. doi:10.1016/S0092-8674(00)80272-X. PMID 9200605. S2CID 10484079.
- ^ a b Wen Y, Yue Z, Shatkin AJ (October 1998). "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. Bibcode:1998PNAS...9512226W. doi:10.1073/pnas.95.21.12226. PMC 22813. PMID 9770468.
- ^ Bisaillon M, Bougie I (September 2003). "Investigating the role of metal ions in the catalytic mechanism of the yeast RNA triphosphatase". The Journal of Biological Chemistry. 278 (36): 33963–71. doi:10.1074/jbc.M303007200. PMID 12819229.
- ^ a b Lima CD, Wang LK, Shuman S (November 1999). "Structure and mechanism of yeast RNA triphosphatase: an essential component of the mRNA capping apparatus". Cell. 99 (5): 533–43. doi:10.1016/S0092-8674(00)81541-X. PMID 10589681. S2CID 1785538.
- ^ a b Karpe YA, Lole KS (September 2010). "RNA 5'-triphosphatase activity of the hepatitis E virus helicase domain". Journal of Virology. 84 (18): 9637–41. doi:10.1128/JVI.00492-10. PMC 2937651. PMID 20592074.
- ^ Barford D, Flint AJ, Tonks NK (March 1994). "Crystal structure of human protein tyrosine phosphatase 1B". Science. 263 (5152): 1397–404. Bibcode:1994Sci...263.1397B. doi:10.1126/science.8128219. PMID 8128219.
- ^ Denu JM, Dixon JE (October 1998). "Protein tyrosine phosphatases: mechanisms of catalysis and regulation". Current Opinion in Chemical Biology. 2 (5): 633–41. doi:10.1016/S1367-5931(98)80095-1. PMID 9818190.
- ^ Deshpande T, Takagi T, Hao L, Buratowski S, Charbonneau H (June 1999). "Human PIR1 of the protein-tyrosine phosphatase superfamily has RNA 5'-triphosphatase and diphosphatase activities". The Journal of Biological Chemistry. 274 (23): 16590–4. doi:10.1074/jbc.274.23.16590. PMID 10347225.
Further reading edit
- Becker A, Hurwitz J (March 1967). "The enzymatic cleavage of phosphate termini from polynucleotides". The Journal of Biological Chemistry. 242 (5): 936–50. doi:10.1016/S0021-9258(18)96215-0. PMID 4289819.
