Rad51-mediated interhomolog recombination during budding yeast meiosis is promoted by the meiotic recombination checkpoint and the conserved Pif1 helicase
Fig 9
Model for Rad51-mediated interhomolog crossovers during meiosis.
(A) Presynaptic filament shown for one side of a DSB in WT cells. Blue lines represent the duplex of one homolog while red lines represent a chromatid from the other homolog. Dots indicate the 5’ ends of the DNA. (B) Nascent D-loop or paranemic joint. (C) Conversion to a mature D-loop by removal of Dmc1 and heteroduplex formation between the invading strand and donor strand of opposite polarity. The question mark indicates that the mechanism for how this occurs is unknown. (D) Extension of the D-loop by DNA synthesis by Polδ-PCNA followed by second end capture. (E) Double Holliday junction. (F) Presynaptic filament shown for one side of a DSB in hedΔR cells with Rad54 interacting with Rad51. (G) Nascent D-loop or paranemic joint. (H) Internal D-loop created by Rad54 removal of Rad51 and heteroduplex formation between the invading strand and donor strand of opposite polarity. (I) Removal of Dmc1 from the 3’ end of the invading strand. (J) Pif1 interacts with PCNA to facilitate DNA synthesis by unwinding the duplex to extend the D-loop allowing second end capture. (K) Double Holliday junction. Not shown is the possibility that the extended ends could be disassembled to enable noncrossover formation by synthesis dependent strand annealing.