Abstract
It has previously been shown that the mitochondrial DNA (mtDNA) of Saccharomyces cerevisiae becomes thermo-sensitive due to the inactivation of the mitochondrial DNA helicase gene, PIF1. A suppressor of this thermosensitive phenotype was isolated from a wild-type plasmid library by transforming a pif1 null strain to growth on glycerol at the non-permissive temperature. This suppressor is a nuclear gene encoding a 135 amino acid protein that is itself essential for mtDNA replication; cells lacking this gene are totally devoid of mtDNA. We therefore named this gene RIM1 for replication in mitochondria. The primary structure of the RIM1 protein is homologous to the single-stranded DNA binding protein (SSB) from Escherichia coli and to the mitochondrial SSB from Xenopus laevis. The mature RIM1 gene product has been purified from yeast extracts using a DNA unwinding assay dependent upon the DNA helicase activity of SV40 T-antigen. Direct amino acid sequencing of the protein reveals that RIM1 is a previously uncharacterized SSB. Antibodies against this purified protein localize REM1 to mitochondria. The SSB encoded by RlM1 is therefore an essential component of the yeast mtDNA replication apparatus.
Original language | English (US) |
---|---|
Pages (from-to) | 3421-3430 |
Number of pages | 10 |
Journal | EMBO Journal |
Volume | 11 |
Issue number | 9 |
State | Published - Sep 1992 |
Externally published | Yes |
All Science Journal Classification (ASJC) codes
- General Neuroscience
- Molecular Biology
- General Biochemistry, Genetics and Molecular Biology
- General Immunology and Microbiology
Keywords
- DNA helicase
- Mitochondrial DNA replication
- Single-stranded DNA binding protein
- Yeast