1exd | pdb_00001exd
CRYSTAL STRUCTURE OF A TIGHT-BINDING GLUTAMINE TRNA BOUND TO GLUTAMINE AMINOACYL TRNA SYNTHETASE
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Overview
Guided by an in vitro selection experiment designed to obtain tight, binding aptamers of Escherichia coli glutamine specific tRNA (tRNAGln) for, glutaminyl-tRNA synthetase (GlnRS), we have engineered a tRNA mutant in, which the five-nucleotide variable loop sequence 5'-44CAUUC48-3' is, replaced by 5'-44AGGU48-3'. This mutant tRNA binds to GlnRS with 30-fold, improved affinity compared to the wild type. The 2.7 A cocrystal structure, of the RNA aptamer-GlnRS complex reveals major rearrangements in the, central tertiary core of the tRNA, while maintaining an RNA-protein, interface identical to the wild type. The repacked RNA core features a, novel hydrogen bonding arrangement of the trans Levitt pair G15-U48, a new, sulfate binding pocket in the major groove, and increased hydrophobic, stacking interactions among the bases. These data suggest that enhanced, protein binding to a mutant globular RNA can arise from stabilization of, RNA tertiary interactions rather than optimization of RNA-protein, contacts.
About this Structure
1EXD is a Single protein structure of sequence from Escherichia coli with SO4 and A as ligands. Active as Glutamine--tRNA ligase, with EC number 6.1.1.18 Full crystallographic information is available from OCA.
Reference
Tertiary core rearrangements in a tight binding transfer RNA aptamer., Bullock TL, Sherlin LD, Perona JJ, Nat Struct Biol. 2000 Jun;7(6):497-504. PMID:10881199
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