Developing a genetic approach to investigate the mechanism of mitochondrial competence for DNA import.
Mitochondrial gene products are essential for the viability of eukaryote obligate aerobes. Consequently, mutations of the mitochondrial genome cause severe diseases in man and generate traits widely used in plant breeding. Pathogenic mutations can often be identified but direct genetic rescue remains impossible because mitochondrial transformation is still to be achieved in higher eukaryotes. Along this line, it has been shown that isolated plant and mammalian mitochondria are naturally competent for importing linear DNA. However, it has proven difficult to understand how such large polyanions cross the mitochondrial membranes. The genetic tractability of Saccharomyces cerevisae could be a powerful tool to unravel this molecular mechanism. Here we show that isolated S. cerevisiae mitochondria can import linear DNA in a process sharing similar characteristics to plant and mammalian mitochondria. Based on biochemical data, translocation through the outer membrane is believed to be mediated by voltage-dependent anion channel (VDAC) isoforms in higher eukaryotes. Both confirming this hypothesis and validating the yeast model, we illustrate that mitochondria from S. cerevisiae strains deleted for the VDAC-1 or VDAC-2 gene are severely compromised in DNA import. The prospect is now open to screen further mutant yeast strains to identify the elusive inner membrane DNA transporter.
Weber-Lotfi
Frédérique
F
Institut de Biologie Moléculaire des Plantes, Université Louis Pasteur, 67084 Strasbourg, France.
Ibrahim
Noha
N
Boesch
Pierre
P
Cosset
Anne
A
Konstantinov
Yuri
Y
Lightowlers
Robert N
RN
Dietrich
André
A
D000818:Animals; D017788:Carlavirus / Q000235:genetics; D004271:DNA, Fungal / Q000235:genetics; D004272:DNA, Mitochondrial / Q000235:genetics*; D018744:DNA, Plant / Q000235:genetics; D017353:Gene Deletion; D016678:Genome; D006801:Humans; D008322:Mammals / Q000235:genetics; D008928:Mitochondria / Q000235:genetics*; D010957:Plasmids; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development; D050995:Voltage-Dependent Anion Channel 1 / Q000235:genetics; D050996:Voltage-Dependent Anion Channel 2 / Q000235:genetics; D050994:Voltage-Dependent Anion Channels / Q000235:genetics; D003313:Zea mays / Q000235:genetics
D004271:DNA, Fungal; D004272:DNA, Mitochondrial; D018744:DNA, Plant; D050996:Voltage-Dependent Anion Channel 2; D050994:Voltage-Dependent Anion Channels; D050995:Voltage-Dependent Anion Channel 1