Misincorporation rate in translation in CAT III mutant

Range 5e-6 - 2e-5 Mismatched/matched amino acid
Organism Budding yeast Saccharomyces cerevisiae
Reference Stansfield I, Jones KM, Herbert P, Lewendon A, Shaw WV, Tuite MF. Missense translation errors in Saccharomyces cerevisiae. J Mol Biol. 1998 Sep 11 282(1):13-24. p.19 right column top paragraph and p.20 right column bottom paragraphPubMed ID9733638
Method Measurement of inactivating mutants of type III chloramphenicol acetyl transferase mutants.
Comments "In order for active CAT enzyme to be produced from the Ala195 mutant allele of CATIII, on the assumption that such a missense error arises through inaccuracy of mRNA decoding, a non-cognate interaction is required between tRNAGUGHis and the GCU Ala codon at position 195, an event that requires mispairing at both the first and the second positions and a G·U wobble pairing at the third position (Figure 2). The unlikely occurrence of such an error made it all the more surprising that a His misincorporation frequency of 2×10^-5 was detected using the Ala195 CATIII allele (Figure 4), a frequency approximately three times the basal His misincorporation event measured using the Tyr195 allele." "The obvious inference from the S. cerevisiae measurements presented here is that not only is the translational missense error frequency substantially lower than the corresponding E. coli value, but the underlying and contributory transcriptional error frequency must also be at least less than 0.5×10^-5, again lower than the prokaryote estimates. Can Saccharomyces (and other eukaryotes?) be regarded as intrinsically more accurate transcribers and translators than E. coli (or other prokaryotes)? An examination of other codon-specific missense error frequency estimates in E. coli would indicate that yeast does not necessarily exhibit a lesser global error frequency. For example, expression in E. coli of the identical CATIII alleles employed in this study yielded estimates for the histidine substitution for tyrosine of 0.5×10^-5 (Lewendon et al., 1994), identical to estimates made here for the same error in yeast. Histidine substitution for alanine at CATIII codon 195 in E. coli occurs at a frequency of 1×10^-6, again a value comparable to the yeast estimate (Lewendon et al., 1994)." 0.000005 for His195(CAC)>Tyr195(UAC) mutant. 0.00002 for His195(CAC)>Ala195(GCU) mutant.
Entered by Uri M
ID 105216