Isolation and characterization of the Schizosaccharomyces pombe cDNA encoding the mitochondrial endonuclease

We isolated the cDNA of the fission yeast mitochondrial endonuclease SpNUC1 , which consists of 322 amino acids and has a significant homology with the budding yeast NUC1 and mammalian endonuclease G. Comparison of the cDNA se quence with the genomic sequence showed that the gene consists of three exo ns and two introns and spans 1.31 kb. The enzyme localization in mitochondr ia was demonstrated by expressing the SpNUC1-green fluorescent protein fusi on in the yeast. The endonuclease was activated by truncation of the aminot erminal region of the protein, indicating that the enzyme is encoded as an inactive precursor. The active enzyme degraded single-stranded DNA and RNA, the activity being dependent on Mg2+ (Mn2+). (C) 2001 Elsevier Science B.V . All rights reserved.