The yeast KEM1 gene encodes a nuclease specific for G4 tetraplex DNA: implication of in vivo functions for this novel DNA structure.

We have previously reported the identification of a G4-DNA-dependent nuclease from S. cerevisiae that recognizes a tetrastranded G4-DNA structure and cuts in a single-stranded region 5' to the G4 structure. We purify this activity to homogeneity and show it to be the product of the S. cerevisiae KEM1 gene, which is also known as SEP1, DST2, XRN1, and RAR5. Since a homozygous deletion of the KEM1 gene blocks meiotic cells at the 4N stage, the finding of these G4-dependent DNA binding and cleavage activities for the KEM1 gene product supports the hypothesis that G4-DNA may play a role in meiosis.