4aca | pdb_00004aca

CRYSTAL STRUCTURE OF TRANSLATION ELONGATION FACTOR SELB FROM METHANOCOCCUS MARIPALUDIS, APO FORM

spinqualitylabelsall models 4aca, resolution 3.15Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4aca is a 4 chain structure with sequence from Atcc 43000. This structure supersedes the now removed PDB entry 1wb2. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: 5GP, DXC, SO4 NonStd Res: CMH Related: 1wb2, 1wb3, 4ac9, 4acb Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed 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. 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:15616587 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Elongation factor

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