1wkb

From Proteopedia

---

Revision as of 03:21, 21 November 2007

proteopedia linkproteopedia link

spinqualitylabelsall models 1wkb, resolution 2.05Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal Structure of Leucyl-tRNA Synthetase from the Archaeon Pyrococcus horikoshii Reveals a Novel Editing Domain Orientation

Overview

The editing domains of the closely homologous leucyl, isoleucyl, and, valyl-tRNA synthetases (LeuRS, IleRS, and ValRS, respectively) contribute, to accurate aminoacylation, by hydrolyzing misformed non-cognate, aminoacyl-tRNAs. The editing domain is inserted at the same point of the, sequence in IleRS, ValRS, and the archaeal/eukaryal LeuRS, but at a, distinct point in the bacterial LeuRS. Here, we showed that LeuRS from the, archaeon Pyrococcus horikoshii has editing activity against the nearly, cognate isoleucine. The conserved Asp332 in the editing domain is crucial, for this activity. A deletion mutant lacking the C-terminal region has, only negligible aminoacylation activity, but retains the full activity of, adenylate synthesis and editing. We determined the crystal structure of, this editing-active, truncated form of P.horikoshii LeuRS at 2.1 A, resolution. The structure revealed that it has a novel editing domain, orientation. The editing domain of P.horikoshii LeuRS is rotated by, approximately 180 degrees (rotational state II), with the, two-beta-stranded linker untwisted by a half-turn, as compared to those in, IleRS and ValRS (rotational state I). This editing domain rotational state, in the archaeal LeuRS is similar to that in the bacterial LeuRS. However, because of the insertion point difference, the orientation of the editing, domain relative to the enzyme core in the archaeal LeuRS differs, completely from that in the bacterial LeuRS. An insertion region specific, to the archaeal/eukaryal LeuRS editing domains interacts with the enzyme, core and stabilizes the unique orientation. Thus, we established that, there are three types of editing domain orientations relative to the, enzyme core, depending on the combination of the editing domain insertion, point (i or ii) and the rotational state (I or II): [i, I] for IleRS and, ValRS, [ii, II] for the bacterial LeuRS, and now [i, II] for the, archaeal/eukaryal LeuRS.

About this Structure

1WKB is a Single protein structure of sequence from Pyrococcus horikoshii with SO4 as ligand. Active as Leucine--tRNA ligase, with EC number 6.1.1.4 Full crystallographic information is available from OCA.

Reference

Crystal structure of leucyl-tRNA synthetase from the archaeon Pyrococcus horikoshii reveals a novel editing domain orientation., Fukunaga R, Yokoyama S, J Mol Biol. 2005 Feb 11;346(1):57-71. Epub 2004 Dec 19. PMID:15663927

Page seeded by OCA on Wed Nov 21 05:29:01 2007