1i6m
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(New page: 200px<br /><applet load="1i6m" size="450" color="white" frame="true" align="right" spinBox="true" caption="1i6m, resolution 1.72Å" /> '''1.7 HIGH RESOLUTION ...)
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Revision as of 14:58, 20 November 2007
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1.7 HIGH RESOLUTION EXPERIMENTAL PHASES FOR TRYPTOPHANYL-TRNA SYNTHETASE COMPLEXED WITH TRYPTOPHANYL-5'AMP
Overview
Native data, anomalous data at three wavelengths and an independent, peak-wavelength data set for SeMet-substituted protein have been collected, from cryoprotected crystals of the TrpRS-adenylate product (TAM) complex, to a resolution limit of 1.7 A. Independent phase sets were developed, using SHARP and improved by solvent flipping with SOLOMON using molecular, envelopes derived from experimental densities for, respectively, peak-wavelength SAD data from four different crystals, MAD data and their, M(S)IRAS combinations with native data. Hendrickson-Lattman, phase-probability coefficients from each phase set were used in BUSTER to, drive maximum-likelihood refinements of well defined parts of the, previously refined room-temperature 2.9 A structure. Maximum-entropy, completion followed by manual rebuilding was then used to generate a model, for the missing segments, bound ligand and solvent molecules., Surprisingly, peak-wavelength SAD experiments produced the smallest phase, errors relative to the refined structures. Selenomethionylated models, deviate from one another by 0.25 A and from the native model by 0.38 A, but all have r.m.s. deviations of approximately 1.0 A from the 2.9 A, model. Difference Fourier calculations between amplitudes from the 300 K, experiment and the new amplitudes at 100 K using 1.7 A model phases show, no significant structural changes arising from temperature variation or, addition of cryoprotectant. The main differences between low- and, high-resolution structures arise from correcting side-chain rotamers in, the core of the protein as well as on the surface. These changes improve, various structure-validation criteria.
About this Structure
1I6M is a Single protein structure of sequence from Geobacillus stearothermophilus with SO4, NH4, TYM and GOL as ligands. Active as Tryptophan--tRNA ligase, with EC number 6.1.1.2 Full crystallographic information is available from OCA.
Reference
High-resolution experimental phases for tryptophanyl-tRNA synthetase (TrpRS) complexed with tryptophanyl-5'AMP., Retailleau P, Yin Y, Hu M, Roach J, Bricogne G, Vonrhein C, Roversi P, Blanc E, Sweet RM, Carter CW Jr, Acta Crystallogr D Biol Crystallogr. 2001 Nov;57(Pt 11):1595-608. Epub, 2001 Oct 25. PMID:11679724
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