Disease relevance of RAD51

• Dmc1 and Rad51, yeast homologs of the E. coli RecA protein, are shown by immunostaining to localize to as many as 64 sites within spread meiotic nuclei [1].
• Treatment of mouse 203G glioma cells with 100 nM of RAD51 antisense ODNs significantly enhanced the radiation-induced cell kill compared to control cells, and cells treated with sense or scrambled ODNs [2].
• Chromosomal integration of LTR-flanked DNA in yeast expressing HIV-1 integrase: down regulation by RAD51 [3].
• Our data allowed the identification of RAD51 as a novel in vitro IN cofactor able to down regulate the activity of this retroviral enzyme, thereby acting as a potential cellular restriction factor to HIV infection [3].
• This review focuses on the biochemical and physical characteristics of DNA strand exchange proteins from three diverse organisms: RecA protein from E. coli, UvsX protein from Bacteriophage T4, and RAD51 protein from Saccharomyces cerevisiae [4].

High impact information on RAD51

• In budding yeasts, there are two BIR pathways, one dependent on the Rad51 recombinase protein and one Rad51 independent; these two repair processes lead to different types of survivors in cells lacking the telomerase enzyme that is required for normal telomere maintenance [5].
• We observed chromosome fusions only in mutant strains expressing Rad51 and Rad55 or when Tel1 was inactivated [6].
• Meiotic recombination requires the meiosis-specific RecA homolog Dmc1 as well as the mitotic RecA homolog Rad51 [7].
• Saccharomyces cerevisiae Mer3 helicase stimulates 3'-5' heteroduplex extension by Rad51; implications for crossover control in meiotic recombination [8].
• Overexpressing SRS2 nearly eliminates crossovers, whereas overexpression of RAD51 in srs2Delta cells almost completely eliminates the noncrossover recombination pathway [9].

Chemical compound and disease context of RAD51

• Remarkably, the mutant cell lines all exhibit very similar phenotypes: spontaneous chromosomal aberrations, high sensitivity to killing by cross-linking agents (mitomycin C and cisplatin), mild sensitivity to gamma rays, and significantly attenuated Rad51 focus formation during recombinational repair after exposure to gamma rays [10].

Biological context of RAD51

• The RAD51 gene of S. cerevisiae is involved in mitotic recombination and repair of DNA damage and also in meiosis [11].
• In the yeast Saccharomyces cerevisiae, mutations in the genes RAD51 or RAD52 result in severe defects in genetic recombination and the repair of double-strand DNA breaks [12].
• Targeted disruption of the murine RAD51 gene results in an embryonic lethal phenotype, indicating that Rad51 protein is required during cell proliferation [12].
• DMC1, RAD51, and ZIP1 encode two RecA homologs and a synaptonemal complex protein, respectively [13].
• We obtained the same phenotype upon introduction of RNAi constructs aimed at silencing the RAD51 gene at meiosis in dmc1 mutant plants [14].

Anatomical context of RAD51

• Unlike chicken RAD52 and mouse RAD51, no significant difference in mouse RAD52 mRNA level was found among mouse heart, brain, spleen, lung, liver, skeletal muscle, kidney, and testis [15].
• Yeast cell-free system that catalyses joint-molecule formation in a Rad51p- and Rad52p-dependent fashion [16].
• With antibodies that have been immunodepleted of cross-reactive epitopes, we demonstrate that RAD51 and DMC1 have identical distribution patterns in extracts of mouse spermatocytes in successive prophase I stages, suggesting coordinate functionality [17].
• We generated clones of the chicken B lymphocyte line DT40 carrying a human RAD51 transgene under the control of a repressible promoter and subsequently disrupted the endogenous RAD51 loci [18].
• RAD51 homologues in Xenopus laevis: two distinct genes are highly expressed in ovary and testis [19].

Associations of RAD51 with chemical compounds

• Transcription of uvsC is induced by methyl-methane sulphonate (MMS), as is transcription of RAD51 of yeast [20].
• The mus-25 mutant is epistatic to the mei-3 mutant for MMS sensitivity. mei-3, which is a homololog of the Saccharomyces cerevisiae gene RAD51, is a member of the uvs-6 epistasis group which contains several genes that are homologous to recombination repair genes in other organisms [21].
• We show here that the Rad54 protein interacts with the Rad51 protein in vivo and in vitro and that the NH2-terminal 115 residues of the Rad54 protein are necessary for this interaction [22].
• Saccharomyces cerevisiae lacking Snm1, Rev3 or Rad51 have a normal S-phase but arrest permanently in G2 after cisplatin treatment [23].
• The pairing and strand exchange reaction requires adenosine triphosphate, a result consistent with the presence of a DNA-dependent adenosine triphosphatase activity in RAD51 protein [24].

Physical interactions of RAD51

• Dmc1 and, by inference, Rad51 form complexes before synapsis as monitored by immunostaining for Zip1 protein [1].
• Yeast Rad52 protein interacts with Rad51 protein, binds single-stranded DNA and stimulates annealing of complementary single-stranded DNA [25].
• Rad55 was shown to interact with Rad51 and Rad57 but not with itself [26].
• These results suggest that the presence of the Rad51 homologous recombination complex in a top3 background facilitates creation of detrimental intermediates by Sgs1 [27].
• Accordingly, N-terminal truncation mutants of Rdh54 that fail to bind Rad51 are also impaired for functional interactions with the latter [28].
• Hed1 binds Rad51 with high affinity and specificity [29].

Enzymatic interactions of RAD51

• Here we used chromatin immunoprecipitation to monitor the in vivo association of Saccharomyces cerevisiae Rad51p with both the cleaved MATa locus and the HML alpha donor [30].
• Rad51 nucleoprotein filaments catalyze DNA strand exchange and Rad54 augments this activity of Rad51 [31].

Regulatory relationships of RAD51

• Rad52 protein stimulates DNA strand exchange by Rad51 and replication protein A [25].
• Yeast Rad55 and Rad57 proteins form a heterodimer that functions with replication protein A to promote DNA strand exchange by Rad51 recombinase [32].
• A class of rad51 alleles was isolated that suppresses the requirement for RAD55 and RAD57 in DNA repair, but not the other accessory factors [33].
• Furthermore, an increased dosage of SWI6 enhanced the transcript level of the RAD51 gene and also the recombination frequency in meiosis [34].
• Rad54 protein stimulated Rad51/Rpa-mediated DNA strand exchange by specifically increasing the kinetics of joint molecule formation [35].

Other interactions of RAD51

• Dmc1 and Rad51 colocalize and are therefore likely to act together during recombination [1].
• The DNA-binding properties of hRad52 indicate that Rad52 is involved in an early stage of Rad51-mediated recombination [12].
• One mutation identified, rad59, reduced recombination 1200-fold in the presence of a rad51 mutation, but only 4- to 5-fold in a wild-type background [36].
• In yeast, mutations of this type include rad50S, dmc1, rad51, and zip1 [13].
• Lack of Rad54p does not significantly impair Rad51p recruitment to MAT or its initial association with HML alpha; however, Rad54p is required at or before the initiation of DNA synthesis after synapsis has occurred at the 3' end of the invading strand [30].

Analytical, diagnostic and therapeutic context of RAD51

• RAD51 relieved the negative dominance of each of these alleles either by competitive titration or functional activation of mutant or heterologous Rad52 proteins [37].
• First, flow cytometric measurements of DNA content and immunofluorescence were used to determine the phase-specific levels of RAD51 and RAD52 protein expression in irradiated and control populations [38].
• To further substantiate this, we measured the induction of the DNA repair gene RAD51 in RAD51-LACZ fusion strains using the dsb repair and recombination deficient mutant rad52 and the corresponding wild type, and we determined the formation of dsb by pulsed-field gel electrophoresis [39].
• Molecular dissection of interactions between Rad51 and members of the recombination-repair group [40].
• Using site-directed mutagenesis of highly conserved residues of human Rad51 (hRad51) and gene targeting of the RAD51 locus in chicken DT40 cells, we examined the importance of Rad51's highly conserved ATP-binding domain [41].

References