Functional attributes of the Saccharomyces cerevisiae meiotic recombinase Dmc1.

The role of Dmc1 as a meiosis-specific general recombinase was first demonstrated in Saccharomyces cerevisiae. Progress in understanding the biochemical mechanism of ScDmc1 has been hampered by its tendency to form inactive aggregates. We have found that the inclusion of ATP during protein purification prevents Dmc1 aggregation. ScDmc1 so prepared is capable of forming D-loops and responsive to its accessory factors Rad54 and Rdh54. Negative staining electron microscopy and iterative helical real-space reconstruction revealed that the ScDmc1-ssDNA nucleoprotein filament harbors 6.5 protomers per turn with a pitch of ∼106à . The ScDmc1 purification procedure and companion molecular analyses should facilitate future studies on this recombinase.