SCHIZOSACCHAROMYCES-POMBE APN1 ENCODES A HOMOLOG OF THE ESCHERICHIA-COLI ENDONUCLEASE-IV FAMILY OF DNA-REPAIR PROTEINS

The Apn1 protein of the budding yeast Saccharomyces cerevisiae is a DN A repair enzyme that hydrolyzes apurinic/apyrimidinic (AP) sites and r emoves 3'-blocking groups present at single strand breaks of damaged D NA. Yeast cells lacking Apn1 are hypersensitive to DNA damaging agents that produce AP sites and DNA strand breaks with blocked 3'-termini. In this study, we showed that the fission yeast Schizosaccharomyces po mbe bears a homologue, Spapn1, that is 45% identical to S. cerevisiae Apn1. However, the Spapn1 gene is apparently not expressed. Active exp ression of S. cerevisiae Apn1 in S. pombe conferred no additional resi stance to DNA damaging agents. These data suggest that the pathway by which S. pombe repairs AP sites is independent of a functional Apn1-li ke AP endonuclease. (C) 1998 Elsevier Science B.V.