Molecular and General Genetics MGG

, Volume 224, Issue 2, pp 209–221

The yeast mitochondrial leucyl-tRNA synthetase is a splicing factor for the excision of several group I introns

  • Michel Labouesse

DOI: 10.1007/BF00271554

Cite this article as:
Labouesse, M. Molec. Gen. Genet. (1990) 224: 209. doi:10.1007/BF00271554


The Saccharomyces cerevisiae nuclear gene NAM2 codes for mitochondrial leucyl-tRNA synthetase (mLRS). Herbert et al. (1988, EMBO J 7:473–483) proposed that this protein is involved in mitochondrial RNA splicing. Here we present the construction and analyses of nine mutations obtained by creating two-codon insertions within the NAM2 gene. Three of these prevent respiration while maintaining the mitochondrial genome. These three mutants: (1) display in vitro a mLRS activity ranging from 0%–50% that of the wild type: (2) allow in vivo the synthesis of several mitochondrially encoded proteins; (3) prevent the synthesis of the COXII protein but not of its mRNA; (4) abolish the splicing of the group I introns bI4 and aI4; and (5) affect significantly the excision of the group I introns bI2, bI3 and aI3. Importation of the bI4 maturase from the cytoplasm into mitochondria in a nam2 mutant strain does not restore the excision of the introns bI4 and aI4 implying that the splicing deficiency does not result from the absence of the bI4 maturase. We conclude that the mLRS is a splicing factor essential for the excision of the group I introns bI4 and aI4 and probably important for the excision of other group I introns.

Key words

Aminoacyl-tRNA synthetase RNA splicing Group I introns RNA maturase Yeast 

Copyright information

© Springer-Verlag 1990

Authors and Affiliations

  • Michel Labouesse
    • 1
  1. 1.Centre de Génétique Moléculaire du C.N.R.S.Laboratoire propre associé à l'Université Pierre et Marie CurieGif Sur-Yvette CedexFrance
  2. 2.Department of Biology M.I.T.CambridgeUSA

Personalised recommendations