Genetic analyses of Schizosaccharomyces pombe dna2(+) reveal that dna2 plays an essential role in Okazaki fragment metabolism

Genetics. 2000 Jul;155(3):1055-67. doi: 10.1093/genetics/155.3.1055.


In this report, we investigated the phenotypes caused by temperature-sensitive (ts) mutant alleles of dna2(+) of Schizosaccharomyces pombe, a homologue of DNA2 of budding yeast, in an attempt to further define its function in vivo with respect to lagging-strand synthesis during the S-phase of the cell cycle. At the restrictive temperature, dna2 (ts) cells arrested at late S-phase but were unaffected in bulk DNA synthesis. Moreover, they exhibited aberrant mitosis when combined with checkpoint mutations, in keeping with a role for Dna2 in Okazaki fragment maturation. Similarly, spores in which dna2(+) was disrupted duplicated their DNA content during germination and also arrested at late S-phase. Inactivation of dna2(+) led to chromosome fragmentation strikingly similar to that seen when cdc17(+), the DNA ligase I gene, is inactivated. The temperature-dependent lethality of dna2 (ts) mutants was suppressed by overexpression of genes encoding subunits of polymerase delta (cdc1(+) and cdc27(+)), DNA ligase I (cdc17(+)), and Fen-1 (rad2(+)). Each of these gene products plays a role in the elongation or maturation of Okazaki fragments. Moreover, they all interacted with S. pombe Dna2 in a yeast two-hybrid assay, albeit to different extents. On the basis of these results, we conclude that dna2(+) plays a direct role in the Okazaki fragment elongation and maturation. We propose that dna2(+) acts as a central protein to form a complex with other proteins required to coordinate the multienzyme process for Okazaki fragment elongation and maturation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphatases / antagonists & inhibitors
  • Adenosine Triphosphatases / genetics*
  • Adenosine Triphosphatases / metabolism
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism
  • Cell Line
  • Chromosomes / genetics
  • DNA / metabolism*
  • DNA Helicases / antagonists & inhibitors
  • DNA Helicases / genetics*
  • DNA Helicases / metabolism
  • DNA Polymerase I / genetics
  • DNA Polymerase I / metabolism
  • DNA Replication / genetics
  • DNA-Binding Proteins*
  • Endodeoxyribonucleases*
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism
  • Gene Dosage
  • Genes, Lethal
  • Genes, cdc
  • Guanine Nucleotide Exchange Factors*
  • Mutagenicity Tests
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / metabolism
  • S Phase / genetics
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae Proteins*
  • Schizosaccharomyces / enzymology*
  • Schizosaccharomyces / genetics*
  • Sequence Analysis, DNA
  • Spores, Fungal / genetics
  • Spores, Fungal / growth & development
  • Temperature
  • Two-Hybrid System Techniques
  • Ultraviolet Rays


  • CDC1 protein, S cerevisiae
  • CDC24 protein, S cerevisiae
  • Cell Cycle Proteins
  • DNA-Binding Proteins
  • Fungal Proteins
  • Guanine Nucleotide Exchange Factors
  • Okazaki fragments
  • Proto-Oncogene Proteins
  • Saccharomyces cerevisiae Proteins
  • RAD2 protein, S cerevisiae
  • DNA
  • DNA Polymerase I
  • POL1 protein, S cerevisiae
  • Endodeoxyribonucleases
  • Adenosine Triphosphatases
  • DNA Helicases
  • DNA2 protein, S cerevisiae