2bcz
From Proteopedia
(New page: 200px<br /><applet load="2bcz" size="350" color="white" frame="true" align="right" spinBox="true" caption="2bcz, resolution 2.40Å" /> '''Crystal Structure of...) |
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==Overview== | ==Overview== | ||
| - | The hairpin ribozyme requires functional group contributions from G8 to | + | The hairpin ribozyme requires functional group contributions from G8 to assist in phosphodiester bond cleavage. Previously, replacement of G8 by a series of nucleobase variants showed little effect on interdomain docking, but a 3-250-fold effect on catalysis. To identify G8 features that contribute to catalysis within the hairpin ribozyme active site, structures for five base variants were determined by X-ray crystallography in a resolution range between 2.3 and 2.7 A. For comparison, a native all-RNA "G8" hairpin ribozyme structure was refined to 2.05 A resolution. The native structure revealed a scissile bond angle (tau) of 158 degrees, which is close to the requisite 180 degrees "in-line" geometry. Mutations G8(inosine), G8(diaminopurine), G8(aminopurine), G8(adenosine), and G8(uridine) folded properly, but exhibited nonideal scissile bond geometries (tau ranging from 118 degrees to 93 degrees) that paralleled their diminished solution activities. A superposition ensemble of all structures, including a previously described hairpin ribozyme-vanadate complex, indicated the scissile bond can adopt a variety of conformations resulting from perturbation of the chemical environment and provided a rationale for how the exocyclic amine of nucleobase 8 promotes productive, in-line geometry. Changes at position 8 also caused variations in the A-1 sugar pucker. In this regard, variants A8 and U8 appeared to represent nonproductive ground states in which their 2'-OH groups mimicked the pro-R, nonbridging oxygen of the vanadate transition-state complex. Finally, the results indicated that ordered water molecules bind near the 2'-hydroxyl of A-1, lending support to the hypothesis that solvent may play an important role in the reaction. |
==About this Structure== | ==About this Structure== | ||
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Water in the active site of an all-RNA hairpin ribozyme and effects of Gua8 base variants on the geometry of phosphoryl transfer., Salter J, Krucinska J, Alam S, Grum-Tokars V, Wedekind JE, Biochemistry. 2006 Jan 24;45(3):686-700. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=16411744 16411744] | Water in the active site of an all-RNA hairpin ribozyme and effects of Gua8 base variants on the geometry of phosphoryl transfer., Salter J, Krucinska J, Alam S, Grum-Tokars V, Wedekind JE, Biochemistry. 2006 Jan 24;45(3):686-700. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=16411744 16411744] | ||
[[Category: Protein complex]] | [[Category: Protein complex]] | ||
| - | [[Category: Salter, J | + | [[Category: Salter, J D.]] |
| - | [[Category: Wedekind, J | + | [[Category: Wedekind, J E.]] |
[[Category: NCO]] | [[Category: NCO]] | ||
[[Category: SO4]] | [[Category: SO4]] | ||
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[[Category: ribozyme]] | [[Category: ribozyme]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 16:36:27 2008'' |
Revision as of 14:36, 21 February 2008
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Crystal Structure of a minimal, mutant all-RNA hairpin ribozyme (U39C, G8I, 2'deoxy A-1)
Overview
The hairpin ribozyme requires functional group contributions from G8 to assist in phosphodiester bond cleavage. Previously, replacement of G8 by a series of nucleobase variants showed little effect on interdomain docking, but a 3-250-fold effect on catalysis. To identify G8 features that contribute to catalysis within the hairpin ribozyme active site, structures for five base variants were determined by X-ray crystallography in a resolution range between 2.3 and 2.7 A. For comparison, a native all-RNA "G8" hairpin ribozyme structure was refined to 2.05 A resolution. The native structure revealed a scissile bond angle (tau) of 158 degrees, which is close to the requisite 180 degrees "in-line" geometry. Mutations G8(inosine), G8(diaminopurine), G8(aminopurine), G8(adenosine), and G8(uridine) folded properly, but exhibited nonideal scissile bond geometries (tau ranging from 118 degrees to 93 degrees) that paralleled their diminished solution activities. A superposition ensemble of all structures, including a previously described hairpin ribozyme-vanadate complex, indicated the scissile bond can adopt a variety of conformations resulting from perturbation of the chemical environment and provided a rationale for how the exocyclic amine of nucleobase 8 promotes productive, in-line geometry. Changes at position 8 also caused variations in the A-1 sugar pucker. In this regard, variants A8 and U8 appeared to represent nonproductive ground states in which their 2'-OH groups mimicked the pro-R, nonbridging oxygen of the vanadate transition-state complex. Finally, the results indicated that ordered water molecules bind near the 2'-hydroxyl of A-1, lending support to the hypothesis that solvent may play an important role in the reaction.
About this Structure
2BCZ is a Protein complex structure of sequences from [1] with and as ligands. Full crystallographic information is available from OCA.
Reference
Water in the active site of an all-RNA hairpin ribozyme and effects of Gua8 base variants on the geometry of phosphoryl transfer., Salter J, Krucinska J, Alam S, Grum-Tokars V, Wedekind JE, Biochemistry. 2006 Jan 24;45(3):686-700. PMID:16411744
Page seeded by OCA on Thu Feb 21 16:36:27 2008
Categories: Protein complex | Salter, J D. | Wedekind, J E. | NCO | SO4 | G8 | Inosine | Ribozyme
