Disease relevance of RAD50

• Structural and functional similarities between the SbcCD proteins of Escherichia coli and the RAD50 and MRE11 (RAD32) recombination and repair proteins of yeast [1].
• Rad50cd crystal structures identify probable protein and DNA interfaces and reveal an ABC-ATPase fold, linking Rad50 molecular mechanisms to ABC transporters, including P glycoprotein and cystic fibrosis transmembrane conductance regulator [2].
• However, large-scale purification of the 153 kDa Rpo41 has only been reported from yeast cells, or as a recombinant from baculovirus, both sources requiring extensive purification with poor yields [3].

High impact information on RAD50

• To clarify the key role of Rad50 in DNA double-strand break repair (DSBR), we biochemically and structurally characterized ATP-bound and ATP-free Rad50 catalytic domain (Rad50cd) from Pyrococcus furiosus [2].
• Permanent arrest in hdf1 cells is suppressed by rad50 or mre11 deletions that retard this degradation [4].
• Saccharomyces Ku70, mre11/rad50 and RPA proteins regulate adaptation to G2/M arrest after DNA damage [4].
• In light of this and other observations, the meiotic and mitotic defects of rad50 mutants can be accounted for economically by the proposal that meiotic recombination, meiotic chromosome pairing, and vegetative DNA repair all use a common chromosomal homology search that involves RAD50 function [5].
• The RAD50 gene of S. cerevisiae is required during meiosis for both recombination and chromosome synapsis and is also required for repair of double strand breaks during vegetative growth [5].

Biological context of RAD50

• Recombination-induced CAG trinucleotide repeat expansions in yeast involve the MRE11-RAD50-XRS2 complex [6].
• Deletion of both RAD50 and RAD51 produces a phenotype similar to that produced by deletion of RAD52 [7].
• Mutations in XRS2 and RAD50 delay but do not prevent mating-type switching in Saccharomyces cerevisiae [8].
• While most of these genes are essential for yeast mating-type (MAT) gene switching, neither RAD50 nor XRS2 is required to complete this specialized mitotic gene conversion process [8].
• RAD50 and RAD51 define two pathways that collaborate to maintain telomeres in the absence of telomerase [9].

Anatomical context of RAD50

• In rad50 delta cells, some DSBs are not repaired until a broken chromosome has been packaged into a spore and is subsequently germinated [10].
• High levels of RAD50 expression was evident in the adult myocardium, a somewhat surprising observation given the absence of DNA synthesis in adult cardiomyocytes [11].

Associations of RAD50 with chemical compounds

• The MRE11, RAD50, and XRS2 genes of Saccharomyces cerevisiae are involved in the repair of DNA double-strand breaks (DSBs) produced by ionizing radiation and by radiomimetic chemicals such as methyl methanesulfonate (MMS) [12].
• The yeast RAD50 gene encodes a predicted 153-kD protein containing a purine nucleotide-binding domain and two large heptad-repeat regions [13].
• In support of this, we found that Rad50 functions in the same pathway for the repair of MMS-induced damage as Rad21, the homologue of the Saccharomyces cerevisiae Scc1 cohesin protein [14].
• Replacement of the conserved lysine residue within the Walker A motif with alanine, glutamate, or arginine results in the same DNA damage sensitivity and homologous recombination defect as the rad50 deletion mutation [15].

Physical interactions of RAD50

• Using a two-hybrid system, we found that Mre11 interacts with Rad50 and itself in vivo [16].

Co-localisations of RAD50

• In response to ionizing radiation, Rad52 relocalizes to form distinctive foci which are distributed throughout the nucleus and which colocalize with Rad50 foci in the DNA damage response [17].

Regulatory relationships of RAD50

• Physical monitoring of DNA showed that SPO13: : HO induced gene conversions both in Rad+ and in rad50 delta cells that cannot initiate normal meiotic DSBs [10].
• These endonuclease activities of Mre11 are enhanced markedly by Rad50 but only in the presence of ATP [18].
• Other LOH events were differentially affected in each mutant: the frequencies of all types of recombination were decreased in rad52 mutants and enhanced in rad50 mutants [19].

Other interactions of RAD50

• Overexpression of Mre11p or Rad50p suppresses the inhibition of DSB repair by CAG(98) and significantly increases the average size of expansions found at the recipient locus [6].
• Using a galactose-inducible HO endonuclease gene to initiate MAT switching, we have examined the effect of null mutations of RAD50 and of XRS2 on intermediate steps of this recombination event [8].
• We have examined the interactions of rem1 mutations with rad6-1, rad50 -1, rad52-1 or spo11 -1 mutations in order to understand the basis of the rem1 hyper-rec phenotype [20].
• Thus RAD50 and RAD51 define two separate pathways that collaborate to allow cells to survive in the absence of telomerase [9].
• A search for highly expressed cDNAs that suppress the DNA repair deficiency of rad50 mutants yielded multiple isolates of two genes: EXO1 and TLC1 [21].

Analytical, diagnostic and therapeutic context of RAD50

• We report here a structural analysis of full-length S. cerevisiae Rad50, alone and in a complex with yeast Mre11 by electron microscopy [22].
• Furthermore, nonribosomal DNA sequences retain their RAD50-dependence even when inserted into the ribosomal DNA array [23].
• Northern blot analyses demonstrated a complex pattern of RAD50 expression during mouse development which was further complicated by the presence of several alternatively spliced transcripts [11].
• Sequence analyses revealed that the clones encoded a protein with regional homology to the yeast RAD50 gene product [11].
• The fission yeast Mre11 complex Rad32p/Rad50p/Nbs1p was also required for efficient capture of mtDNA at DSBs, supporting a role for the complex in promoting intermolecular ligation [24].

References