Poly(A) Polymerase
From Proteopedia
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==About this Structure== | ==About this Structure== | ||
| - | 2Q66 is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Saccharomyces_cerevisiae Saccharomyces cerevisiae]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2Q66 OCA]. | + | 2Q66 is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Saccharomyces_cerevisiae Saccharomyces cerevisiae]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2Q66 OCA]. |
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| + | ==Determinants of ATP Recognition== | ||
| + | Poly(A) polymerase binds specifically to ATP and adds it the end of a messenger RNA chain. This structure contains an oligo(A) polynucleotide with five nucleotides, an ATP molecule, and a magnesium ion. The enzyme is an inactive mutant with the catalytic aspartate 154 changed to alanine. In the <scene name='Goodsell_Sandbox/2q66_summary/1'>summary picture</scene>, the enzyme is in blue backbone representation, the RNA chain is in yellow, the ATP is in red, the magnesium is in green, and ALA154 is in magenta. Several mechanisms are used to achieve the specificity for ATP. The magnesium is coordinated by <scene name='Goodsell_Sandbox/2q66_asp/3'>ASP100 and ASP102</scene>, and the magnesium coordinates with the phosphates of ATP, positioning the nucleotide in the active site. The adenine base is sandwiched between the <scene name='Goodsell_Sandbox/2q66_stacking/2'>terminal base of the RNA (in yellow) and VAL234 (in cyan)</scene>. Surprisingly, there are very few contacts with the hydrogen-bonding groups in the adenine base. <scene name='Goodsell_Sandbox/2q66_asn/1'>ASN 236</scene> may form a hydrogen bond to adenine in the active enzyme, but the distance it a bit too long in this mutant structure. Instead of forming specific hydrogen bonds with the enzyme, most of the hydrogen-bonding groups in the base, sugar and phosphate interact with a shell of <scene name='Goodsell_Sandbox/2q66_water/2'>buried water molecules</scene>. Discrimination between ATP and GTP is achieved through a close steric contact between the <scene name='Goodsell_Sandbox/2q66_c2/3'>adenine C2 (in white) and the sidechains of THR 304 and MET310 (shown in cyan)</scene>. Guanine bases have an extra amino group at this position that would be too bulky to fit against these amino acids. | ||
==Reference== | ==Reference== | ||
Revision as of 16:37, 12 September 2008
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| 2q66, resolution 1.80Å () | |||||||||
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| Ligands: | , , | ||||||||
| Gene: | PAP1 (Saccharomyces cerevisiae) | ||||||||
| Activity: | Polynucleotide adenylyltransferase, with EC number 2.7.7.19 | ||||||||
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| Resources: | FirstGlance, OCA, RCSB, PDBsum | ||||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||||
Contents |
Structure of Yeast Poly(A) Polymerase with ATP and oligo(A)
Template:ABSTRACT PUBMED 17850751
About this Structure
2Q66 is a Single protein structure of sequence from Saccharomyces cerevisiae. Full crystallographic information is available from OCA.
Determinants of ATP Recognition
Poly(A) polymerase binds specifically to ATP and adds it the end of a messenger RNA chain. This structure contains an oligo(A) polynucleotide with five nucleotides, an ATP molecule, and a magnesium ion. The enzyme is an inactive mutant with the catalytic aspartate 154 changed to alanine. In the , the enzyme is in blue backbone representation, the RNA chain is in yellow, the ATP is in red, the magnesium is in green, and ALA154 is in magenta. Several mechanisms are used to achieve the specificity for ATP. The magnesium is coordinated by , and the magnesium coordinates with the phosphates of ATP, positioning the nucleotide in the active site. The adenine base is sandwiched between the . Surprisingly, there are very few contacts with the hydrogen-bonding groups in the adenine base. may form a hydrogen bond to adenine in the active enzyme, but the distance it a bit too long in this mutant structure. Instead of forming specific hydrogen bonds with the enzyme, most of the hydrogen-bonding groups in the base, sugar and phosphate interact with a shell of . Discrimination between ATP and GTP is achieved through a close steric contact between the . Guanine bases have an extra amino group at this position that would be too bulky to fit against these amino acids.
Reference
Mechanism of poly(A) polymerase: structure of the enzyme-MgATP-RNA ternary complex and kinetic analysis., Balbo PB, Bohm A, Structure. 2007 Sep;15(9):1117-31. PMID:17850751
Page seeded by OCA on Sun Jul 27 17:16:40 2008
Proteopedia Page Contributors and Editors (what is this?)
Michal Harel, Eran Hodis, David Canner, Joel L. Sussman, OCA, Alexander Berchansky, Jaime Prilusky, David S. Goodsell, Eric Martz
