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Mol. Cell. Biol., Jan 1998, 260-268, Vol 18, No. 1
H Tsubouchi and H Ogawa
Using complementation tests and nucleotide sequencing, we showed that the
rad58-4 mutation was an allele of the MRE11 gene and have renamed the
mutation mre11-58. Two amino acid changes from the wild-type sequence were
identified; one is located at a conserved site of a phosphodiesterase
motif, and the other is a homologous amino acid change at a nonconserved
site. Unlike mre11 null mutations, the mre11- 58 mutation allowed
meiosis-specific double-strand DNA breaks (DSBs) to form at recombination
hot spots but failed to process those breaks. DSB ends of this mutant were
resistant to lambda exonuclease treatment. These phenotypes are similar to
those of rad50S mutants. In contrast to rad50S, however, mre11-58 was
highly sensitive to methyl methanesulfonate treatment. DSB end processing
induced by HO endonuclease was suppressed in both mre11-58 and the mre11
disruption mutant. We constructed a new mre11 mutant that contains only the
phosphodiesterase motif mutation of the Mre11-58 protein and named it
mre11-58S. This mutant showed the same phenotypes observed in mre11-58,
suggesting that the phosphodiesterase consensus sequence is important for
nucleolytic processing of DSB ends during both mitosis and meiosis.
Copyright © 1998, American Society for Microbiology
A novel mre11 mutation impairs processing of double-strand breaks of DNA during both mitosis and meiosis
Department of Biology, Graduate School of Science, Osaka University, Toyonaka, Japan.
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