1qrs
|
GLUTAMINYL-TRNA SYNTHETASE MUTANT D235N COMPLEXED WITH GLUTAMINE TRANSFER RNA
OverviewOverview
Three previously described mutant Escherichia coli glutaminyl-tRNA synthetase (GlnRS) proteins that incorrectly aminoacylate the amber suppressor derived from tRNATyr (supF) with glutamine were cocrystallized with wild-type tRNAGln and their structures determined. In two of the mutant enzymes studied, Asp235, which contacts base pair G3-C70 in the acceptor stem, has been changed to asparagine in GlnRS7 and to glycine in GlnRS10. These mutations result in changed interactions between Asn235 of GlnRS7 and G3-C70 of the tRNA and an altered water structure between Gly235 of GlnRS10 and base pair G3-C70. These structures suggest how the mutant enzymes can show only small changes in their ability to aminoacylate wild-type cognate tRNA on the one hand and yet show a lack of discrimination against a noncognate U3-A70 base pair on the other. In contrast, the change of Ile129 to Thr in GlnRS15 causes virtually no change in the structure of the complex, and the explanation for its ability to misacylate supF is unclear.
About this StructureAbout this Structure
1QRS is a Single protein structure of sequence from Escherichia coli with as ligand. Active as Glutamine--tRNA ligase, with EC number 6.1.1.18 Full crystallographic information is available from OCA.
ReferenceReference
Crystal structures of three misacylating mutants of Escherichia coli glutaminyl-tRNA synthetase complexed with tRNA(Gln) and ATP., Arnez JG, Steitz TA, Biochemistry. 1996 Nov 26;35(47):14725-33. PMID:8942633
Page seeded by OCA on Thu Feb 21 14:42:58 2008