The affinity of elongation factor Tu for an aminoacyl-tRNA is modulated by the esterified amino acid.
When different mutations were introduced into the anticodon loop and at position 73 of YFA2, a derivative of yeast tRNA(Phe), a single tRNA body was misacylated with 13 different amino acids. The affinities of these misacylated tRNAs for Thermus thermophilus elongation factor Tu (EF-Tu).GTP were determined using a ribonuclease protection assay. A range of 2.5 kcal/mol in the binding energies was observed, clearly demonstrating that EF-Tu specifically recognizes the side chain of the esterified amino acid. Furthermore, this specificity can be altered by introducing a mutation in the amino acid binding pocket on the surface of EF-Tu. Also, when discussed in conjunction with the previously determined specificity of EF-Tu for the tRNA body, these experiments further demonstrate that EF-Tu uses thermodynamic compensation to bind cognate aminoacyl-tRNAs similarly.
Dale
Taraka
T
Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, Illinois 60208, USA.
Sanderson
Lee E
LE
Uhlenbeck
Olke C
OC
D000596:Amino Acids / Q000737:chemistry* / Q000378:metabolism; D000926:Anticodon; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D008958:Models, Molecular; D015394:Molecular Structure; D016297:Mutagenesis, Site-Directed; D009690:Nucleic Acid Conformation; D010444:Peptide Elongation Factor Tu / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D012346:RNA, Transfer, Amino Acyl / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013816:Thermodynamics; D016963:Thermus thermophilus / Q000235:genetics / Q000378:metabolism
D000596:Amino Acids; D000926:Anticodon; D001426:Bacterial Proteins; D012346:RNA, Transfer, Amino Acyl; D010444:Peptide Elongation Factor Tu