Molecular cloning and genetic characterization of the Saccharomyces cerevisiae NGS1/MRE11 gene.
The Saccharomyces cerevisiae ngs1-1 mutant was previously identified by its enhanced sensitivity to simple DNA-alkylating agents such as methyl methanesulfonate but not to UV. Molecular cloning and sequencing of NGS1 as a putative DNA-alkylation repair gene revealed that it isidentical to MRE11, a gene that is involved in DNA recombinational repair. In order to investigate functional domains of the Mre11 protein, nucleotide-sequence alterations of a number of mre11 mutant alleles, including ngs1-1, mre11-1 (ts), mre11-2, mre11-3 and mre11-58, were determined. Most of these mutations map to the N-terminus ofMre11, emphasizing the importance of this highly conserved domain. The ngs1-1 and mre11-3 mutants carry nonsense mutations resulting in truncated proteins. Missense mutations were found in mre11-1 (ts), mre11-2 and mre11-58, of which mre11-2 and mre11-58 mapped to the conserved phosphoesterase domains, indicating the involvement of these motifs in the formation and/or processing of DNA double-strand breaks. Finally, mitotic-recombination assays show that the mre11 delta mutation enhances inter-chromosomal recombination but decreases the intra-chromosomal deletion frequency. In addition, MRE11 appears to play different roles during spontaneous and alkylation-induced homologous mitotic recombination.
Chamankhah
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Department of Microbiology, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK, S7N 5E5, Canada.
Xiao
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D018906:Antineoplastic Agents, Alkylating / Q000009:adverse effects; D015825:Chromosomes, Fungal / Q000187:drug effects / Q000235:genetics; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair / Q000235:genetics; D004706:Endodeoxyribonucleases; D005090:Exodeoxyribonucleases; D005656:Fungal Proteins / Q000235:genetics*; D005800:Genes, Fungal / Q000235:genetics*; D008741:Methyl Methanesulfonate / Q000009:adverse effects; D009154:Mutation; D011995:Recombination, Genetic / Q000187:drug effects; D012091:Repetitive Sequences, Nucleic Acid; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins
D018906:Antineoplastic Agents, Alkylating; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; D004247:DNA; D008741:Methyl Methanesulfonate; D004706:Endodeoxyribonucleases; D005090:Exodeoxyribonucleases; C094191:MRE11 protein, S cerevisiae