Molecular and General Genetics MGG

, Volume 264, Issue 1, pp 137–144

Critical base substitutions that affect the splicing and/or homing activities of the group I intron bi2 of yeast mitochondria

  • T. Szczepanek
  • K. Jamoussi
  • J. Lazowska
Original Paper

DOI: 10.1007/s004380000297

Cite this article as:
Szczepanek, T., Jamoussi, K. & Lazowska, J. Mol Gen Genet (2000) 264: 137. doi:10.1007/s004380000297

Abstract

The second intron (bi2) of the cyt b gene from related Saccharomyces species has an extraordinarily conserved sequence and can have different functions in wild-type cells. The protein encoded by the S. cerevisiae intron functions as a maturase to promote intron splicing, while the homologous S. capensis intron encodes a bifunctional protein that acts both as a maturase and as a homing endonuclease (I-ScaI) promoting intron mobility. The protein encoded by intron bi2 belongs to a large gene family characterized by the presence of two conserved LAGLIDADG motifs (P1 and P2). In this study, we analysed a set of splicing-deficient mutants of the S. cerevisiae intron bi2 that carry non-directed mutations affecting the maturase activity, and a set of directed missense mutations introduced into the bifunctional protein encoded by the S. capensis intron. Analysis of these mutations has allowed identification of the residues in the conserved P1 and P2 motifs which are crucial for splicing and homing activities. Moreover, several mutations which are located in the C-terminal part of the protein have been found to affect both functions.

Group I intron Maturase/Homing endonuclease Intronic protein mutations Yeast Mitochondria

Copyright information

© Springer-Verlag 2000

Authors and Affiliations

  • T. Szczepanek
    • 1
  • K. Jamoussi
    • 1
  • J. Lazowska
    • 1
  1. 1.Centre de Génétique Moléculaire du CNRS, 91198 Gif-sur-Yvette CedexFrance