Specific alterations of the EF‐Tu polypeptide chain considered in the light of its three‐dimensional structure

• Published in: The EMBO journal 1984-01, Vol.3 (1), p.113-120
• Main Authors: Duisterwinkel, F.J., Kraal, B., De Graaf, J.M., Talens, A., Bosch, L., Swart, G.W., Parmeggiani, A., La Cour, T.F., Nyborg, J., Clark, B.F.
• Format: Article
• Language: English
• Subjects: amino acids; Amino Acids - analysis; Biological and medical sciences; DNA Restriction Enzymes; elongation factor Tu; Escherichia coli - drug effects; Escherichia coli - genetics; Fundamental and applied biological sciences. Psychology; Kinetics; kirromycin; Methylnitronitrosoguanidine - pharmacology; Models, Molecular; Molecular and cellular biology; Molecular genetics; mutants; Mutation; Peptide Elongation Factor Tu; Peptide Elongation Factors - genetics; Peptide Fragments - analysis; protein biosynthesis; Protein Biosynthesis - drug effects; Protein Conformation; Pyridones - pharmacology; Species Specificity; Translation. Translation factors. Protein processing
• ISSN: 0261-4189; 1460-2075
• DOI: 10.1002/j.1460-2075.1984.tb01770.x

Specific alterations of the elongation factor Tu (EF‐Tu) polypeptide chain have been identified in a number of mutant species of this elongation factor. In two species, Ala‐375, located on domain II, was found by amino acid analysis to be replaced by Thr and Val, respectively. These replacements substantially lower the affinity of EF‐Tu.GDP for the antibiotic kirromycin. Since kirromycin can be cross‐linked to Lys‐357, also located on domain II but structurally very far from Ala‐375, these data suggest that the replacements alter the relative position of domains I and II. The Ala‐375 replacements also lower the dissociation rates of the binary complexes EF‐Tu.GTP and the binding constants for EF‐Tu.GTP and Phe‐tRNA. It is conceivable that these effects are also mediated by movements of domains I and II relative to each other. Replacement of Gly‐222 by Asp has been found in another mutant by DNA sequence analysis of the cloned tufB gene, coding for this mutant EF‐Tu. Gly‐222 is part of a structural domain, characteristic for a variety of nucleotide binding enzymes. Its replacement by Asp does not abolish the ability of EF‐Tu to sustain protein synthesis. It increases the dissociation rate of EF‐Tu.GTP by approximately 30%. In the presence of kirromycin this mutant species of EF‐Tu.GDP does not bind to the ribosome, in contrast to its wild‐type counterpart. A possible explanation is now open for experimental verification.