Finding the Correct Partner: The Meiotic Courtship

Figure 1

Homologous recombination during meiosis. Meiotic recombination begins with a break made by Spo11 in one of the two double-strand DNA molecules of one chromosome. The 5′ ends of this break are resected leaving tails of 3′ single-strand DNA. When the 3′ ssDNA invade a homologous chromatid, the presence of the Sgs1 protein can reverse the strand inversion intermediates to form a noncrossover outcome or promotes association of some legitimate strand invasion intermediates with the ZMM protein complex. These molecules are resolved in a crossover, mainly by MutL𝛾-Exo1. Molecules formed in the absence of Sgs1 are the target of Mus81-Mms4, Yen1, and Slx1–Slx4, which resolve in a random mode to give both crossover and noncrossover outcomes.