Homologous recombination (HR) is a major DNA repair pathway and therefore essential for maintaining the integrity of the genome. HR is catalyzed by proteins encoded by genes of the RAD52 epistasis group, including the recombinase Rad51 and its mediator Rad52. HR proteins fused with green fluorescent protein form foci at damaged DNA reflecting the assembly of repair centers that harbor a high concentration of repair proteins. Rad52 mediates the recruitment of Rad51 and other HR proteins to DNA damage. To understand the mechanism for the assembly of Rad52-dependent DNA repair centers, we used a mutational strategy to identify a Rad52 domain essential for its recruitment to DNA repair foci. We present evidence to implicate an acidic domain in Rad52 in DNA repair focus formation. Mutations in this domain confer marked DNA damage sensitivity and recombination deficiency. Importantly, these Rad52 mutants are specifically compromised for interaction with the single-stranded DNA-binding factor RPA. Based on these findings, we propose a model where Rad52 displaces RPA from single-stranded DNA using the acidic domain as a molecular lever.In eukaryotes, DNA double strand break (DSB) 4 repair is essential for maintaining genetic stability. The major pathway of DSB repair in the yeast Saccharomyces cerevisiae is homologous recombination (HR), and the evolutionarily conserved proteins involved in this process are encoded by members of the RAD52 epistasis group, including RAD50, RAD51, RAD52, RAD54, RAD55, RAD57, RAD59, RDH54/TID1, RFA1, MRE11, and XRS2 (1). In mitotic cells, most DSBs are eliminated by the synthesis-dependent strand annealing pathway of HR (2). The first step of this pathway involves resection of the ends at the DSB to produce a pair of 3Ј-single-stranded tails. Subsequently, one of these single-stranded tails invades an intact homologous double-stranded DNA sequence to produce a D-loop. DNA polymerase extends the invading end, hence acquiring DNA information that is complementary to the noninvading end. At this stage, the invading strand is dissociated from the invaded duplex and anneals to the noninvading end of the break. Repair is completed when the break is sealed via additional DNA synthesis and ligation.In vitro it has been shown that Rad51 can catalyze the DNA strand invasion reaction via a filamentous intermediate called the presynaptic filament (3, 4). The efficiency of this reaction is dependent on several accessory factors, including the heterotrimeric single-stranded DNA-binding protein RPA (3, 5-7). RPA minimizes intramolecular secondary structure in the singlestranded DNA (ssDNA) that would otherwise impede presynaptic filament assembly. Paradoxically, if an amount of RPA sufficient to saturate the ssDNA is added to the in vitro recombination reaction prior to or together with Rad51, it strongly inhibits strand invasion by limiting access of Rad51 to the ssDNA (1, 8). Chromatin immunoprecipitation and cytological studies have also shown that RPA excludes Rad51 from the HR substrate (9, 10 -13...

A helical filament of Rad51 on single-strand DNA (ssDNA), called the presynaptic filament, catalyzes DNA joint formation during homologous recombination. Rad52 facilitates presynaptic filament assembly, and this recombination mediator activity is thought to rely on the interactions of Rad52 with Rad51, the ssDNA-binding protein RPA, and ssDNA. The N-terminal region of Rad52, which has DNA binding activity and an oligomeric structure, is thought to be crucial for mediator activity and recombination. Unexpectedly, we find that the C-terminal region of Rad52 also harbors a DNA binding function. Importantly, the Rad52 C-terminal portion alone can promote Rad51 presynaptic filament assembly. The middle portion of Rad52 associates with DNAbound RPA and contributes to the recombination mediator activity. Accordingly, expression of a protein species that harbors the middle and C-terminal regions of Rad52 in the rad52 ⌬327 background enhances the association of Rad51 protein with a HO-made DNA double-strand break and partially complements the methylmethane sulfonate sensitivity of the mutant cells. Our results provide a mechanistic framework for rationalizing the multi-faceted role of Rad52 in recombination and DNA repair.

Rad52 is essential for all homologous recombination and DNA double strand break repair events in Saccharomyces cerevisiae. This protein is multifunctional and contains several domains that allow it to interact with DNA as well as with different repair proteins. However, it has been unclear how Rad52 enters the nucleus. In the present study, we have used a combination of mutagenesis and sequence analysis to show that Rad52 from S. cerevisiae contains a single functional pat7 type NLS essential for its nuclear localization. The region containing the NLS seems only to be involved in nuclear transport as it plays no role in repair of MMS-induced DNA damage. The NLS in Rad52 is weak, as monomeric protein species that harbor this NLS are mainly located in the cytosol. In contrast, multimeric protein complexes wherein each subunit contains a single NLS(Rad52) sort efficiently to the nucleus. Based on the results we propose a model where the additive effect of multiple NLS(Rad52) sequences in a Rad52 ring-structure ensures efficient nuclear localization of Rad52.

Coloplast has conducted a qualitative study among health professionals working in the field of continence care. Interviews with health professionals working in urology and rehabilitation provided insights into the barriers to, and supporters of, adherent behaviour—suggesting ways in which health professionals can work with patients performing intermittent self-catheterisation (ISC) to support better adherence. This includes individualised training that addresses individual fears, ensures correct understanding of the body and the treatment, and eliminates misconceptions. They can also help patients set realistic ambitions, and give them practical advice that will help them adapt ISC to their daily life. Patients need to know how to handle urinary tract infections, how to cope with contradictory instructions from other sources, and how to identify support resources and accurate information. Specific challenges relating to support for urology patients and rehabilitation patients were also highlighted.

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