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==MODEL OF A HYPOTHESIZED HAMMERHEAD RIBOZYME CONFORMATIONAL CHANGE== | |||
<StructureSection load='1fg1' size='340' side='right' caption='[[1fg1]]' scene=''> | |||
== Structural highlights == | |||
<table><tr><td colspan='2'>For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1FG1 FirstGlance]. <br> | |||
</td></tr><tr><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1fg1 FirstGlance], [http://www.ebi.ac.uk/pdbsum/1fg1 PDBsum]</span></td></tr> | |||
<table> | |||
<div style="background-color:#fffaf0;"> | |||
== Publication Abstract from PubMed == | |||
We have constructed a model structure that we believe represents the strongest possible physically and chemically reasonable representation of a hypothesized catalytically active hammerhead ribozyme structure in which a single divalent metal ion bridges the A9 and scissile phosphate groups. It has been proposed that such a structure arises from a conformational change in which the so-called ground-state structure (as observed by X-ray crystallography) rearranges in such a way that the pro-R oxygen atoms of both the A9 and scissile phosphate groups are directly coordinated by a single divalent metal ion in the transition-state of the hammerhead ribozyme cleavage reaction. We show that even the small subset of possible model structures that are consistent with these requirements, and that are stereochemically and sterically reasonable, are contradicted by experimental evidence. We also demonstrate that even a minimal subset of assumptions, i.e. that stems I and II are helical and that the two phosphate groups are coordinated by a divalent metal ion in the standard octahedral geometry, are sufficient to lead to this contradiction. We therefore conclude that such a mechanism of hammerhead ribozyme catalysis is untenable, at least in its present formulation. | |||
Does a single metal ion bridge the A-9 and scissile phosphate groups in the catalytically active hammerhead ribozyme structure?,Murray JB, Scott WG J Mol Biol. 2000 Feb 11;296(1):33-41. PMID:10656816<ref>PMID:10656816</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
</div> | |||
== References == | |||
<references/> | |||
__TOC__ | |||
</StructureSection> | |||
== | |||
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[[Category: Murray, J B]] | [[Category: Murray, J B]] | ||
[[Category: Scott, W G]] | [[Category: Scott, W G]] | ||
Revision as of 16:01, 28 September 2014
MODEL OF A HYPOTHESIZED HAMMERHEAD RIBOZYME CONFORMATIONAL CHANGEMODEL OF A HYPOTHESIZED HAMMERHEAD RIBOZYME CONFORMATIONAL CHANGE
Structural highlights
Publication Abstract from PubMedWe have constructed a model structure that we believe represents the strongest possible physically and chemically reasonable representation of a hypothesized catalytically active hammerhead ribozyme structure in which a single divalent metal ion bridges the A9 and scissile phosphate groups. It has been proposed that such a structure arises from a conformational change in which the so-called ground-state structure (as observed by X-ray crystallography) rearranges in such a way that the pro-R oxygen atoms of both the A9 and scissile phosphate groups are directly coordinated by a single divalent metal ion in the transition-state of the hammerhead ribozyme cleavage reaction. We show that even the small subset of possible model structures that are consistent with these requirements, and that are stereochemically and sterically reasonable, are contradicted by experimental evidence. We also demonstrate that even a minimal subset of assumptions, i.e. that stems I and II are helical and that the two phosphate groups are coordinated by a divalent metal ion in the standard octahedral geometry, are sufficient to lead to this contradiction. We therefore conclude that such a mechanism of hammerhead ribozyme catalysis is untenable, at least in its present formulation. Does a single metal ion bridge the A-9 and scissile phosphate groups in the catalytically active hammerhead ribozyme structure?,Murray JB, Scott WG J Mol Biol. 2000 Feb 11;296(1):33-41. PMID:10656816[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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