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| {{STRUCTURE_1d2r| PDB=1d2r | SCENE= }} | | {{STRUCTURE_1d2r| PDB=1d2r | SCENE= }} |
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| '''2.9 A CRYSTAL STRUCTURE OF LIGAND-FREE TRYPTOPHANYL-TRNA SYNTHETASE: DOMAIN MOVEMENTS FRAGMENT THE ADENINE NUCLEOTIDE BINDING SITE.'''
| | ===2.9 A CRYSTAL STRUCTURE OF LIGAND-FREE TRYPTOPHANYL-TRNA SYNTHETASE: DOMAIN MOVEMENTS FRAGMENT THE ADENINE NUCLEOTIDE BINDING SITE.=== |
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| ==Overview==
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| The crystal structure of ligand-free tryptophanyl-tRNA synthetase (TrpRS) was solved at 2.9 A using a combination of molecular replacement and maximum-entropy map/phase improvement. The dimeric structure (R = 23.7, Rfree = 26.2) is asymmetric, unlike that of the TrpRS tryptophanyl-5'AMP complex (TAM; Doublie S, Bricogne G, Gilmore CJ, Carter CW Jr, 1995, Structure 3:17-31). In agreement with small-angle solution X-ray scattering experiments, unliganded TrpRS has a conformation in which both monomers open, leaving only the tryptophan-binding regions of their active sites intact. The amino terminal alphaA-helix, TIGN, and KMSKS signature sequences, and the distal helical domain rotate as a single rigid body away from the dinucleotide-binding fold domain, opening the AMP binding site, seen in the TAM complex, into two halves. Comparison of side-chain packing in ligand-free TrpRS and the TAM complex, using identification of nonpolar nuclei (Ilyin VA, 1994, Protein Eng 7:1189-1195), shows that significant repacking occurs between three relatively stable core regions, one of which acts as a bearing between the other two. These domain rearrangements provide a new structural paradigm that is consistent in detail with the "induced-fit" mechanism proposed for TyrRS by Fersht et al. (Fersht AR, Knill-Jones JW, Beduelle H, Winter G, 1988, Biochemistry 27:1581-1587). Coupling of ATP binding determinants associated with the two catalytic signature sequences to the helical domain containing the presumptive anticodon-binding site provides a mechanism to coordinate active-site chemistry with relocation of the major tRNA binding determinants.
| | The line below this paragraph, {{ABSTRACT_PUBMED_10716174}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 10716174 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_10716174}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Induced fit]] | | [[Category: Induced fit]] |
| [[Category: Trpr]] | | [[Category: Trpr]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 13:23:08 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jun 30 22:13:38 2008'' |
