1i9t
CRYSTAL STRUCTURE OF THE OXIDIZED RNA TRIPHOSPHATASE DOMAIN OF MOUSE MRNA CAPPING ENZYME
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| , resolution 1.7Å | |||||||
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| Ligands: | , , , , | ||||||
| Activity: | Polynucleotide 5'-phosphatase, with EC number 3.1.3.33 | ||||||
| Related: | 1I9S
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| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
OverviewOverview
The 5' capping of mammalian pre-mRNAs is initiated by RNA triphosphatase, a member of the cysteine phosphatase superfamily. Here we report the 1.65 A crystal structure of mouse RNA triphosphatase, which reveals a deep, positively charged active site pocket that can fit a 5' triphosphate end. Structural, biochemical and mutational results show that despite sharing an HCxxxxxR(S/T) motif, a phosphoenzyme intermediate and a core alpha/beta-fold with other cysteine phosphatases, the mechanism of phosphoanhydride cleavage by mammalian capping enzyme differs from that used by protein phosphatases to hydrolyze phosphomonoesters. The most significant difference is the absence of a carboxylate general acid catalyst in RNA triphosphatase. Residues conserved uniquely among the RNA phosphatase subfamily are important for function in cap formation and are likely to play a role in substrate recognition.
About this StructureAbout this Structure
1I9T is a Single protein structure of sequence from Mus musculus. Full crystallographic information is available from OCA.
ReferenceReference
Structure and mechanism of the RNA triphosphatase component of mammalian mRNA capping enzyme., Changela A, Ho CK, Martins A, Shuman S, Mondragon A, EMBO J. 2001 May 15;20(10):2575-86. PMID:11350947
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