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Nucleic Acids Res. 1986 Oct 10;14(19):7529-39.

The proofreading of hydroxy analogues of leucine and isoleucine by leucyl-tRNA synthetases from E. coli and yeast.

Abstract

Three analogues each of leucine and isoleucine carrying hydroxy groups in gamma- or delta- or gamma- and delta-position have been synthesized, and tested in the aminoacylation by leucyl-tRNA synthetases from E. coli and yeast. Hydrolytic proofreading, as proposed in the chemical proofreading model, of these analogues and of homocysteine should result in a lactonisation of these compounds and therefore provide information regarding the proofreading mechanism of the two leucyl-tRNA synthetases. Leucyl-tRNA synthetase from E. coli shows a high initial substrate discrimination. Only two analogues, gamma-hydroxyleucine and homocysteine are activated and transferred to tRNALeu where a post-transfer proofreading occurs. Lactonisation of gamma-hydroxyleucine and homocysteine could be detected. Leucyl-tRNA synthetase from yeast has a relatively poor initial discrimination of these substrates, which is compensated by a very effective pre-transfer proofreading on the aminoacyl-adenylate level. No lactonisation nor mischarged tRNALeu is detectable.

PMID:
3534789
PMCID:
PMC311778
DOI:
10.1093/nar/14.19.7529
[Indexed for MEDLINE]
Free PMC Article

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