Idiosyncrasy and identity in the prokaryotic phe-system: Crystal structure of E. coli phenylalanyl-tRNA synthetase complexed with phenylalanine and AMP
✍ Scribed by Inbal Mermershtain; Igal Finarov; Liron Klipcan; Naama Kessler; Haim Rozenberg; Mark G. Safro
- Publisher
- Cold Spring Harbor Laboratory Press
- Year
- 2010
- Tongue
- English
- Weight
- 360 KB
- Volume
- 20
- Category
- Article
- ISSN
- 0961-8368
- DOI
- 10.1002/pro.549
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
The crystal structure of Phenylalanyl‐tRNA synthetase from E. coli (__Ec__PheRS), a class II aminoacyl‐tRNA synthetase, complexed with phenylalanine and AMP was determined at 3.05 Å resolution. __Ec__PheRS is a (αβ)~2~ heterotetramer: the αβ heterodimer of __Ec__PheRS consists of 11 structural domains. Three of them: the N‐terminus, A1 and A2 belong to the α‐subunit and B1‐B8 domains to the β subunit. The structure of __Ec__PheRS revealed that architecture of four helix‐bundle interface, characteristic of class IIc heterotetrameric aaRSs, is changed: each of the two long helices belonging to CLM transformed into the coil‐short helix structural fragments. The N‐terminal domain of the α‐subunit in __Ec__PheRS forms compact triple helix domain. This observation is contradictory to the structure of the apo form of __Tt__PheRS, where N‐terminal domain was not detected in the electron density map. Comparison of __Ec__PheRS structure with __Tt__PheRS has uncovered significant rearrangements of the structural domains involved in tRNA^Phe^ binding/translocation. As it follows from modeling experiments, to achieve a tighter fit with anticodon loop of tRNA, a shift of ∼5 Å is required for C‐terminal domain B8, and of ∼6 to 7 Å for the whole N terminus. __Ec__PheRSs have emerged as an important target for the incorporation of novel amino acids into genetic code. Further progress in design of novel compounds is anticipated based on the structural data of __Ec__PheRS.