This entry represents Spo11, a meiotic recombination protein found in eukaryotes, and subunit A of topoisomerase VI, a type IIB topoisomerase found predominantly in archaea [10545127, 12618182]. These two types of proteins share structural homology.
DNA topoisomerases regulate the number of topological links between two DNA strands (i.e. change the number of superhelical turns) by catalysing transient single- or double-strand breaks, crossing the strands through one another, then resealing the breaks. They can be divided into two classes: type I enzymes (, topoisomerases I, III and V) break single-strand DNA, and type II enzymes (, topoisomerases II, IV and VI) break double-strand DNA . Topoisomerase VI is a type IIB enzymes that assembles as a heterotetramer, consisting of two A subunits required for DNA cleavage and two B subunits required for ATP hydrolysis. The B subunit is structurally similar to the ATPase domain of type IIA topoisomerases, but the A subunit is distinct, and instead shares homology with the Spo11 protein.
Spo11 is a meiosis-specific protein that is responsible for the initiation of recombination through the formation of DNA double-strand breaks by a type II DNA topoisomerase-like activity. Spo11 acts in conjunction with several other proteins, including Rec102 in yeast, to bring about meiotic recombination .
More information about this protein can be found at Protein of the Month: DNA Topoisomerase.