Maintenance and stabilization of mtDNA can be facilitated by the DNA-binding activity of Ilv5p.
Mitochondrial DNA (mtDNA) is inherited as a protein-DNA complex (the nucleoid). Proteins associated with the nucleoid are not only components directly involved in maintenance and propagation of mtDNA but can also be bi-functional enzymes whose metabolic activities are not directly related to mtDNA stability. In the yeast Saccharomyces cerevisiae, one such enzyme, Ilv5p is required for branch chain amino acid biosynthesis but also associates with the nucleoid. Deletions of ILV5 lead not only to metabolic defects but also to destabilization of mtDNA. Further, minor overproduction of Ilv5p stabilizes mtDNA in strains lacking Abf2p, a major mtDNA binding and packaging protein. Here we show that Ilv5p binds double-stranded DNA in vitro and is unaffected by the presence of saturating concentrations of Abf2p. In cells lacking Abf2p the amount of Ilv5p associated with the nucleoid increases significantly and is proportional to the mitochondrial concentration of Ilv5p. Altogether, we conclude that direct binding of Ilv5p can aid in the maintenance and stabilization of mtDNA.
Macierzanka
Malgorzata
M
Department of Molecular and Cellular Biology, Faculty of Biotechnology, University of Gdansk, 24 Kladki, Gdansk 80822PL, Poland.
Plotka
Magdalena
M
Pryputniewicz-Drobinska
Diana
D
Lewandowska
Agnieszka
A
Lightowlers
Robert
R
Marszalek
Jaroslaw
J
D000429:Alcohol Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D004272:DNA, Mitochondrial / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D011485:Protein Binding; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D013696:Temperature; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014364:Tryptophan / Q000235:genetics / Q000378:metabolism
C072843:ABF2 protein, S cerevisiae; D004272:DNA, Mitochondrial; D004268:DNA-Binding Proteins; D024101:Mitochondrial Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D014364:Tryptophan; D000429:Alcohol Oxidoreductases; C470636:Ilv5 protein, S cerevisiae