Impaired in vitro kinetics of EF-Tu mutant Aa.
The kirromycin-resistant EF-Tu mutant Aa, previously shown to be an antisuppressor for nonsense and missense suppressor tRNAs, has been characterised in a poly(U)-primed translation system in vitro. Two major defects were found in the function of the mutant. First, the dissociation constant for Aa binding to Phe-tRNA(Phe) was increased tenfold compared to wild-type EF-Tu. Second, kcat/Km for the interaction between the EF-Tu.GTP.aa-tRNA complex and the ribosome was decreased by the mutation to one third of its wild-type value. No differences were observed between mutant and wild-type factor in the regeneration of EF-Tu.GTP from EF-Tu.GDP via EF-Ts or in the mistranslation frequency by Leu-tRNA(4Leu). The relation between the in vitro results and the mutant phenotype in vivo is discussed.
Tapio
S
S
Department of Microbiology, University of Uppsala, Sweden.
Bilgin
N
N
Ehrenberg
M
M
D001426:Bacterial Proteins / Q000096:biosynthesis; D001665:Binding Sites; D004351:Drug Resistance; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D007700:Kinetics; D010452:Peptide Biosynthesis; D010444:Peptide Elongation Factor Tu / Q000235:genetics* / Q000502:physiology; D010445:Peptide Elongation Factors / Q000378:metabolism; D010641:Phenotype; D014176:Protein Biosynthesis / Q000502:physiology*; D011728:Pyridones / Q000494:pharmacology; D012343:RNA, Transfer / Q000378:metabolism; D012345:RNA, Transfer, Amino Acid-Specific / Q000378:metabolism; D012269:Ribosomal Proteins / Q000378:metabolism; D013489:Suppression, Genetic
D001426:Bacterial Proteins; D010445:Peptide Elongation Factors; D011728:Pyridones; D012345:RNA, Transfer, Amino Acid-Specific; D012269:Ribosomal Proteins; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D012343:RNA, Transfer; D010444:Peptide Elongation Factor Tu; C008536:mocimycin