Keep moving and stay in a good shape to find your homologous recombination partner.

Genomic DNA is constantly exposed to damage. Among the lesion in DNA, double-strand breaks (DSB), because they disrupt the two strands of the DNA double helix, are the more dangerous. DSB are repaired through two evolutionary conserved mechanisms: Non-Homologous End Joining (NHEJ) and Homologous Recombination (HR). Whereas NHEJ simply reseals the double helix with no or minimal processing, HR necessitates the formation of a 3'ssDNA through the processing of DSB ends by the resection machinery and relies on the recognition and pairing of this 3'ssDNA tails with an intact homologous sequence. Despite years of active research on HR, the manner by which the two homologous sequences find each other in the crowded nucleus, and how this modulates HR efficiency, only recently emerges. Here, we review recent advances in our understanding of the factors limiting the search of a homologous sequence during HR.