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| [[Image:1wb3.gif|left|200px]]<br /><applet load="1wb3" size="350" color="white" frame="true" align="right" spinBox="true" | | #REDIRECT [[4acb]] This PDB entry is obsolete and replaced by 4acb |
| caption="1wb3, resolution 3.20Å" />
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| '''CRYSTAL STRUCTURE OF TRANSLATION ELONGATION FACTOR SELB FROM METHANOCOCCUS MARIPALUDIS IN COMPLEX WITH THE GTP ANALOGUE GPPNHP'''<br />
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| ==Overview==
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| In all three kingdoms of life, SelB is a specialized translation elongation factor responsible for the cotranslational incorporation of selenocysteine into proteins by recoding of a UGA stop codon in the presence of a downstream mRNA hairpin loop. Here, we present the X-ray structures of SelB from the archaeon Methanococcus maripaludis in the apo-, GDP- and GppNHp-bound form and use mutational analysis to investigate the role of individual amino acids in its aminoacyl-binding pocket. All three SelB structures reveal an EF-Tu:GTP-like domain arrangement. Upon binding of the GTP analogue GppNHp, a conformational change of the Switch 2 region in the GTPase domain leads to the exposure of SelB residues involved in clamping the 5' phosphate of the tRNA. A conserved extended loop in domain III of SelB may be responsible for specific interactions with tRNA(Sec) and act as a ruler for measuring the extra long acceptor arm. Domain IV of SelB adopts a beta barrel fold and is flexibly tethered to domain III. The overall domain arrangement of SelB resembles a 'chalice' observed so far only for initiation factor IF2/eIF5B. In our model of SelB bound to the ribosome, domain IV points towards the 3' mRNA entrance cleft ready to interact with the downstream secondary structure element.
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| ==About this Structure==
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| 1WB3 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Methanococcus_maripaludis Methanococcus maripaludis] with <scene name='pdbligand=MG:'>MG</scene>, <scene name='pdbligand=SO4:'>SO4</scene>, <scene name='pdbligand=GNP:'>GNP</scene> and <scene name='pdbligand=DXC:'>DXC</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Known structural/functional Site: <scene name='pdbsite=AC1:Dxc+Binding+Site+For+Chain+C'>AC1</scene>. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1WB3 OCA].
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| ==Reference==
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| Selenocysteine tRNA-specific elongation factor SelB is a structural chimaera of elongation and initiation factors., Leibundgut M, Frick C, Thanbichler M, Bock A, Ban N, EMBO J. 2005 Jan 12;24(1):11-22. Epub 2004 Dec 23. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=15616587 15616587]
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| [[Category: Methanococcus maripaludis]]
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| [[Category: Single protein]]
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| [[Category: Ban, N.]]
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| [[Category: Boeck, A.]]
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| [[Category: Frick, C.]]
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| [[Category: Leibundgut, M.]]
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| [[Category: Thanbichler, M.]]
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| [[Category: DXC]]
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| [[Category: GNP]]
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| [[Category: MG]]
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| [[Category: SO4]]
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| [[Category: protein synthesis]]
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| [[Category: ribosome]]
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| [[Category: selenium]]
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| [[Category: selenocysteine]]
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| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:42:21 2008''
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This PDB entry is obsolete and replaced by 4acb