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spinqualitylabelsall models 1wxw, resolution 2.55Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal structure of Tt1595, a putative SAM-dependent methyltransferase from Thermus thermophillus HB8

Overview

The Thermus thermophilus hypothetical protein TTHA1280 belongs to a family, of predicted S-adenosyl-L-methionine (AdoMet) dependent RNA, methyltransferases (MTases) present in many bacterial and archaeal, species. Inspection of amino-acid sequence motifs common to class I, Rossmann-fold-like MTases suggested a specific role as an RNA, 5-methyluridine MTase. Selenomethionine (SeMet) labelled and native, versions of the protein were expressed, purified and crystallized. Two, crystal forms of the SeMet-labelled apoprotein were obtained: SeMet-ApoI, and SeMet-ApoII. Cocrystallization of the native protein with, S-adenosyl-L-homocysteine (AdoHcy) yielded a third crystal form, Native-AdoHcy. The SeMet-ApoI structure was solved by the multiple, anomalous dispersion method and refined at 2.55 A resolution. The, SeMet-ApoII and Native-AdoHcy structures were solved by molecular, replacement and refined at 1.80 and 2.60 A, respectively. TTHA1280 formed, a homodimer in the crystals and in solution. Each subunit folds into a, three-domain structure composed of a small N-terminal PUA domain, a, central alpha/beta-domain and a C-terminal Rossmann-fold-like MTase, domain. The three domains form an overall clamp-like shape, with the, putative active site facing a deep cleft. The architecture of the active, site is consistent with specific recognition of uridine and catalysis of, methyl transfer to the 5-carbon position. The cleft is suitable in size, and charge distribution for binding single-stranded RNA.

About this Structure

1WXW is a Single protein structure of sequence from Thermus thermophilus with HEZ as ligand. Full crystallographic information is available from OCA.

Reference

Structures of a putative RNA 5-methyluridine methyltransferase, Thermus thermophilus TTHA1280, and its complex with S-adenosyl-L-homocysteine., Pioszak AA, Murayama K, Nakagawa N, Ebihara A, Kuramitsu S, Shirouzu M, Yokoyama S, Acta Crystallograph Sect F Struct Biol Cryst Commun. 2005 Oct 1;61(Pt, 10):867-74. Epub 2005 Sep 30. PMID:16511182

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