Mutation of msh-2 in Neurospora crassa does not reduce the incidence of recombinants with multiple patches of donor chromosome sequence.
The Neurospora homologue msh-2 of the Escherichia coli mismatch repair gene mutS was mutated by repeat-induced point mutation (RIP) of a 1.9-kb duplication covering 1661bp of the coding sequence and 302 bp 5' of the gene. msh-2(RIP-LK1) exhibited a mutator phenotype conferring a 17-fold increase in the frequency of spontaneous mitotic reversion of his-3 allele K458. In msh-2(RIP-LK1) homozygotes, recombination frequency at the his-3 locus increased up to 2.9-fold over that in msh-2(+) diploids. Progeny of crosses homozygous msh-2(RIP-LK1), like those from crosses homozygous msh-2(+) frequently had multiple patches of donor chromosome sequence, suggesting that patchiness in msh-2(+) crosses is not explained by incomplete repair of heteroduplex DNA by MSH-2. These findings are consistent with data from the analysis of events in a Neurospora translocation heterozygote that suggested multiple patches of donor chromosome sequence arising during recombination reflect multiple template switches during DNA repair synthesis.
Koh
Lin Y
LY
School of Biological Sciences, Flinders University, PO Box 2100, Adelaide, SA 5001, Australia.
Catcheside
David E A
DE
D000595:Amino Acid Sequence; D020137:Base Pair Mismatch; D015825:Chromosomes, Fungal / Q000235:genetics; D003434:Crossing Over, Genetic; D053843:DNA Mismatch Repair; D004271:DNA, Fungal / Q000235:genetics*; D005656:Fungal Proteins / Q000235:genetics*; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D051718:MutS Homolog 2 Protein / Q000235:genetics*; D009492:Neurospora crassa / Q000235:genetics*; D017354:Point Mutation; D011995:Recombination, Genetic; D016415:Sequence Alignment; D013698:Templates, Genetic
D004271:DNA, Fungal; D005656:Fungal Proteins; D051718:MutS Homolog 2 Protein