2kx8

<StructureSection load='2kx8' size='340' side='right' caption='[[2kx8]], [[NMR_Ensembles_of_Models | 10 NMR models]]' scene=''>

<table><tr><td colspan='2'>[[2kx8]] is a 1 chain structure. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2KX8 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=2KX8 FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=ARG:ARGININE'>ARG</scene></td></tr>

<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=2kx8 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2kx8 OCA], [http://pdbe.org/2kx8 PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=2kx8 RCSB], [http://www.ebi.ac.uk/pdbsum/2kx8 PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=2kx8 ProSAT]</span></td></tr>

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== Publication Abstract from PubMed ==

The 7SK small nuclear RNA is a highly conserved non-coding RNA that regulates transcriptional elongation. 7SK utilizes the HEXIM proteins to sequester the transcription factor P-TEFb by a mechanism similar to that used by retroviral TAR RNA to engage Tat and P-TEFb. Tat has also recently been shown to bind 7SK directly and recruit P-TEFb to TAR. We report here the solution structures of the free and arginine-bound forms of stem loop 4 of 7SK (7SK-SL4). Comparison of the 7SK-SL4 and TAR structures demonstrates the presence of a common arginine sandwich motif. However, arginine binding to 7SK-SL4 is mechanistically distinct and occurs via docking into a pre-organized pocket resulting in a 1000-fold increased affinity. Furthermore, whereas formation of the binding pocket in TAR requires a critical base-triple, hydrogen-bond formation between the equivalent bases in 7SK-SL4 is not essential and the pocket is stabilized solely by a pseudo base-triple platform. In addition, this theme of preformed protein binding motifs also extends into the pentaloop. The configuration of the loop suggests that 7SK-SL4 is poised to make ternary contacts with P-TEFb and HEXIM or Tat. These key differences between 7SK-SL4 and TAR present an opportunity to understand RNA structural adaptation and have implications for understanding differential interactions with Tat.

Preformed protein-binding motifs in 7SK snRNA: structural and thermodynamic comparisons with retroviral TAR.,Durney MA, D'Souza VM J Mol Biol. 2010 Dec 10;404(4):555-67. Epub 2010 Sep 15. PMID:20816986<ref>PMID:20816986</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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<div class="pdbe-citations 2kx8" style="background-color:#fffaf0;"></div>

== References ==

<references/>

[[Category: Durney, M A]]

[[Category: Souza, V M.D]]

[[Category: Rna]]

[[Category: Snrna]]