1kmn
From Proteopedia
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[[Image:1kmn.gif|left|200px]] | [[Image:1kmn.gif|left|200px]] | ||
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'''HISTIDYL-TRNA SYNTHETASE COMPLEXED WITH HISTIDINOL AND ATP''' | '''HISTIDYL-TRNA SYNTHETASE COMPLEXED WITH HISTIDINOL AND ATP''' | ||
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[[Category: Francklyn, C S.]] | [[Category: Francklyn, C S.]] | ||
[[Category: Moras, D.]] | [[Category: Moras, D.]] | ||
- | [[Category: | + | [[Category: Aminoacyl-trna synthase]] |
- | [[Category: | + | [[Category: Ligase]] |
- | [[Category: | + | [[Category: Synthetase]] |
- | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 22:55:16 2008'' | |
- | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + |
Revision as of 19:55, 2 May 2008
HISTIDYL-TRNA SYNTHETASE COMPLEXED WITH HISTIDINOL AND ATP
Overview
The crystal structure of an enzyme-substrate complex with histidyl-tRNA synthetase from Escherichia coli, ATP, and the amino acid analog histidinol is described and compared with the previously obtained enzyme-product complex with histidyl-adenylate. An active site arginine, Arg-259, unique to all histidyl-tRNA synthetases, plays the role of the catalytic magnesium ion seen in seryl-tRNA synthetase. When Arg-259 is substituted with histidine, the apparent second order rate constant (kcat/Km) for the pyrophosphate exchange reaction and the aminoacylation reaction decreases 1,000-fold and 500-fold, respectively. Crystals soaked with MnCl2 reveal the existence of two metal binding sites between beta- and gamma-phosphates; these sites appear to stabilize the conformation of the pyrophosphate. The use of both conserved metal ions and arginine in phosphoryl transfer provides evidence of significant early functional divergence of class II aminoacyl-tRNA synthetases.
About this Structure
1KMN is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
The first step of aminoacylation at the atomic level in histidyl-tRNA synthetase., Arnez JG, Augustine JG, Moras D, Francklyn CS, Proc Natl Acad Sci U S A. 1997 Jul 8;94(14):7144-9. PMID:9207058 Page seeded by OCA on Fri May 2 22:55:16 2008