Using complementation tests and nucleotide sequencing, we showed that the rad58-4 mutation was an allele of MRE11 gene have renamed mutationmre11-58. Two amino acid changes from wild-type sequence were identified; one is located at a conserved site phosphodiesterase motif, other homologous change nonconserved site. Unlike mre11 null mutations, mre11-58 allowed meiosis-specific double-strand DNA breaks (DSBs) to form recombination hot spots but failed process those breaks. DSB ends this...

The MRE11, RAD50, andXRS2 genes of Saccharomyces cerevisiaeare involved in the repair DNA double-strand breaks (DSBs) produced by ionizing radiation and radiomimetic chemicals such as methyl methanesulfonate (MMS). In these mutants, single-strand degradation a 5′ to 3′ direction from DSB ends is reduced. Multiple copies EXO1 gene, encoding exonuclease, were found suppress high MMS sensitivity mutants. exo1 single mutant shows weak sensitivity. When an mutation combined with anmre11 mutation,...

The hop2 mutant of Saccharomyces cerevisiae arrests in meiosis with extensive synaptonemal complex (SC) formation between nonhomologous chromosomes. A screen for multicopy suppressors a hop2-ts allele identified the MND1 gene. mnd1-null meiotic prophase, most double-strand breaks (DSBs) unrepaired. low level mature recombinants is produced, and Rad51 protein accumulates at numerous foci along SC incomplete, homolog pairing severely reduced. Mnd1 localizes to chromatin throughout this...

In budding yeast, there are two RecA homologs: Rad51 and Dmc1. While is involved in both mitotic meiotic recombination, Dmc1 participates specifically recombination. Here, we describe a meiosis-specific protein (Hed1) with novel regulatory function. Several observations indicate that Hed1 attenuates activity when absent. First, although double-strand breaks normally poorly repaired the dmc1 mutant, repair becomes efficient absent, this effect depends on Rad51. Second, colocalize as foci...

Two RecA orthologs, Rad51 and Dmc1, mediate homologous recombination in meiotic cells. During budding yeast meiosis, Hed1 coordinates the actions of Dmc1 by down-regulating activity. It is thought that Hed1-dependent attenuation facilitates formation crossovers are necessary for correct segregation chromosomes at first division. We purified order to elucidate its mechanism action. binds with high affinity specificity. show does not adversely affect assembly presynaptic filament, but it...

During meiosis, homologous chromosomes pair at close proximity to form the synaptonemal complex (SC). This association is mediated by transverse filament proteins that hold axes of together along their entire length. Transverse are highly aggregative and can an aberrant aggregate called polycomplex unassociated with chromosomes. Here, we show Ecm11-Gmc2 a novel SC component, functioning facilitate assembly yeast protein, Zip1. Ecm11 Gmc2 initially localize synapsis initiation sites, then...

The synaptonemal complex (SC) is a widely conserved structure that mediates the intimate alignment of homologous chromosomes during meiotic prophase and required for proper homolog segregation at meiosis I. However, fundamental details SC architecture assembly remain poorly understood. coiled-coil protein, Zip1, only component whose arrangement within mature budding yeast has been extensively characterized. It proposed Small Ubiquitin-like MOdifier, SUMO, plays role in by linking chromosome...

Abstract Here we provide evidence that the Mei5 and Sae3 proteins of budding yeast act together with Dmc1, a meiosis-specific, RecA-like recombinase. The mei5 sae3 mutations reduce sporulation, spore viability, crossing over to same extent as dmc1. In all three mutants, these defects are largely suppressed by overproduction Rad51. addition, sae3, like dmc1, suppress cell-cycle arrest phenotype hop2 mutant. Mei5, Sae3, Dmc1 colocalize foci on meiotic chromosomes, their localization is...

During meiotic prophase I, proteinaceous structures called synaptonemal complexes (SCs) connect homologous chromosomes along their lengths via polymeric arrays of transverse filaments (TFs). Thus, control TF polymerization is central to SC formation. Using budding yeast, we show that efficiency closely correlates with the extent SUMO conjugation Ecm11, a component SCs. HyperSUMOylation Ecm11 leads highly aggregative TFs, causing frequent assembly extrachromosomal structures. In contrast,...

Budding yeast Pch2 protein is a widely conserved meiosis-specific whose role implicated in the control of formation and displacement meiotic crossover events. In contrast to previous studies where function was steps after double-strand breaks (DSBs) are formed, we present evidence that involved DSB formation, initiation step recombination. The reduction caused by pch2 mutation most prominent sae2 mutant background, whereas impact remains mild rad51 dmc1 double background. further pronounced...

During meiosis, recombination events that occur between homologous chromosomes help prepare the chromosome pairs for proper disjunction in meiosis I. The concurrent action of Rad51 and Dmc1 recombinases is necessary an interhomolog bias. Notably, activity tightly controlled, so as to minimize use sister chromatid partner. We demonstrated recently Hed1, a meiosis-specific protein Saccharomyces cerevisiae, restricts access recombinase accessory factor Rad54 presynaptic filaments Rad51. now...

Abstract During homologous recombination, Rad51 forms a nucleoprotein filament on single-stranded DNA to promote strand exchange. This binds double-stranded (dsDNA), searches for homology, and promotes transfer of the complementary strand, producing new heteroduplex. Strand exchange proceeds via two distinct three-strand intermediates, C1 C2. contains intact donor dsDNA whereas C2 newly formed heteroduplex DNA. Here, we show that conserved binding motifs, loop 1 (L1) 2 (L2) in site I Rad51,...

Significance A DNA double-strand break (DSB) can be repaired accurately by homologous recombination. The Mre11-Rad50-Nbs1 (MRN) complex is responsible for initiating recombination degrading 5′-ended strand, where its activation the Ctp1 cofactor plays a pivotal role. Here, using purified fission yeast proteins, we show that two major elements comprise MRN activation. First, phosphorylation of promotes physical interaction between and Ctp1. Second, C terminus activates nucleolytic processing...

Meiotic recombination plays an essential role in the proper segregation of chromosomes at meiosis I many sexually reproducing organisms. is initiated by scheduled formation genome-wide DNA double-strand breaks (DSBs). The timing DSB strictly controlled because unscheduled detrimental to genome integrity. Here, we investigated damage checkpoint mechanisms control meiotic using budding yeast. By defective mutants which DSBs are not repaired, effect mutations on was evaluated. Tel1 (ATM)...

Significance Homologous recombination (HR) is highly induced during meiosis as it plays an essential role in segregating chromosomes at the first division of meiosis. Dmc1 major enzyme responsible for homology searching and strand exchange However, cell, cannot function without two auxiliary factors, Hop2-Mnd1 Swi5-Sfr1. How these factors collaborate to facilitate Dmc1’s activity remained elusive. Here, we demonstrate that allows access initiate invasion into homologous dsDNA while Swi5-Sfr1...

Homologous recombination (HR) is essential for maintaining genome stability. Although Rad51 the key protein that drives HR, multiple auxiliary factors interact with to potentiate its activity. Here, we present an interdisciplinary characterization of interactions between and these factors. Through structural analysis, identified evolutionarily conserved acidic patch Rad51. The neutralization this completely abolished recombinational DNA repair due defects in recruitment damage sites. This...

Abstract In meiosis, Dmc1 recombinase and the general Rad51 are responsible for pairing homologous chromosomes exchanging strands. Fission yeast (Schizosaccharomyces pombe) Swi5-Sfr1 Hop2-Mnd1 stimulate Dmc1-driven recombination, but stimulation mechanism is unclear. Using single-molecule fluorescence resonance energy transfer (smFRET) tethered particle motion (TPM) experiments, we showed that individually enhance filament assembly on single-stranded DNA (ssDNA) adding both proteins together...

Although Rad51 is the key protein in homologous recombination (HR), a major DNA double-strand break repair pathway, several auxiliary factors interact with to promote productive HR. We present an interdisciplinary characterization of interaction between and Swi5-Sfr1, conserved factor. Two distinct sites within intrinsically disordered N-terminus Sfr1 (Sfr1N) were found cooperatively bind Rad51. Deletion this domain impaired stimulation vitro rendered cells sensitive damage. By contrast,...