Spo11dependent

Spo11dependent refers to cellular processes that require Spo11-catalyzed double-strand breaks to initiate recombination, most prominently during meiotic prophase I in eukaryotes. Spo11 is a conserved topoisomerase-like enzyme that creates DSBs by forming a covalent protein-DNA intermediate at the break site. It functions with accessory factors to promote breaks at defined chromosomal locations, setting the stage for homologous recombination.

Mechanistically, Spo11-dependent recombination begins with the formation of DSBs, which are then processed by the MRN complex along with Sae2/CtIP to produce 3′ single-stranded DNA overhangs. These overhangs are coated by recombinases such as RAD51 and DMC1, enabling strand invasion, homologous pairing, and repair through crossover or noncrossover pathways. The number, timing, and distribution of Spo11-induced breaks are tightly regulated during meiotic prophase to ensure accurate chromosome pairing (synapsis) and segregation.

Spo11-dependent versus Spo11-independent: The term emphasizes the canonical pathway in which meiotic recombination initiates from Spo11-catalyzed DSBs. In some species or experimental settings, recombination can occur without Spo11 through alternative nucleases or replication-associated mechanisms, but such Spo11-independent events are generally less efficient and do not substitute for normal meiosis. Spo11-dependent DSB formation is highly conserved and central to generating genetic diversity while maintaining genome integrity.

Regulation and significance: Spo11 activity is coordinated with the cell cycle and DNA damage checkpoints; improper regulation can lead to meiotic arrest, chromosomal missegregation, or genome instability. Understanding Spo11dependent pathways informs broader insights into meiosis, evolution, and fertility.