Success of homologous recombination-based DNA repair depends not only on recombinases, which promote invasion of the homologous DNA duplex that serves as a template for repair, but also on antirecombinases, which dismantle recombination intermediates to allow completion of repair. In this issue, Barber et al. (2008) identify a previously elusive antirecombinase activity important for maintainin...

The occurrence of homologous DNA recombination in chloroplasts is well documented, but little is known about the molecular mechanisms involved or their biological significance. The endosymbiotic origin of plastids and the recent finding of an Arabidopsis nuclear gene, encoding a chloroplast-localized protein homologous to Escherichia coli RecA, suggest that the plastid recombination system is r...

Mammalian RAD51 protein plays essential roles in DNA homologous recombination, DNA repair and cell proliferation. RAD51 activities are regulated by its associated proteins. It was previously reported that a ubiquitin-like protein, UBL1, associates with RAD51 in the yeast two-hybrid system. One function of UBL1 is to covalently conjugate with target proteins and thus modify their function. In th...

A DNA gap repair assay was used to determine the effect of mutations in the DNA damage checkpoint system on the efficiency and outcome (crossover/non-crossover) of recombinational DNA repair. In Saccharomyces cerevisiae gap repair is largely achieved by homologous recombination. As a result the plasmid either integrates into the chromosome (indicative of a crossover outcome) or remains extrachr...

agrobacterium tumefaciens is capable to transfer genes across kingdoms. it can genetically transform not only plant cells, but also many other bacterial, algal, fungal, animal and human cells. this depends on the interactions among a variety of both agrobacterium and host genes. inside the host cell, rad52 which is involved in dna repair is a key gene determining integration of t-dna by homolog...

Homologous recombination functions universally in the maintenance of genome stability through the repair of DNA breaks and in ensuring the completion of replication. In some organisms, homologous recombination can perform more specific functions. One example of this is in antigenic variation, a widely conserved mechanism for the evasion of host immunity. Trypanosoma brucei, the causative agent ...

DNA double-strand breaks (DSBs) are dangerous lesions that can lead to genomic instability and cell death. Eukaryotic cells repair DSBs either by nonhomologous end-joining (NHEJ) or by homologous recombination. We investigated the ability of yeast cells (Saccharomyces cerevisiae) to repair a single, chromosomal DSB by recombination at different stages of the cell cycle. We show that cells arres...

Methylating agents such as N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and methyl methane sulfonate (MMS) produce a wide variety of N- and O-methylated bases in DNA, some of which can block replication fork progression. Homologous recombination is a mechanism by which chromosome replication can proceed despite the presence of lesions. The two major recombination pathways, RecBCD and RecFOR, whi...