Two distinct DNA ligase activities in mitotic extracts of the yeast Saccharomyces cerevisiae

William Ramos, Nancy Tappe, Jose Talamantez, Errol C. Friedberg, Alan E. Tomkinson

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


Four biochemically distinct DNA ligases have been identified in mammalian cells. One of these enzymes, DNA ligase I, is functionally homologous to the DNA ligase encoded by the Saccharomyces cerevisiae CDC9 gene. Cdc9 DNA ligase has been assumed to be the only species of DNA ligase in this organism. In the present study we have identified a second DNA ligase activity in mitotic extracts of S. cerevisiae with chromategraphic properties different from Cdc9 DNA ligase, which is the major DNA joining activity. This minor DNA joining activity, which contributes 5-10% of the total cellular DNA joining activity, forms a 90 kDa enzyme-adenylate intermediate which, unlike the Cdc9 enzyme-adenylate intermediate, reacts with an oligo (pdT)/poly (rA) substrate. The levels of the minor DNA joining activity are not altered by mutation or by overexpression of the CDC9 gene. Furthermore, the 90 kDa polypeptide is not recognized by a Cdc9 antiserum. Since this minor species does not appear to be a modified form of Cdc9 DNA ligase, it has been designated as S. cerevisiae DNA ligase II. Based on the similarities in polynucleotide substrate specificity, this enzyme may be the functional homolog of mammalian DNA ligase III or IV.

Original languageEnglish (US)
Pages (from-to)1485-1492
Number of pages8
JournalNucleic acids research
Issue number8
StatePublished - Apr 15 1997

ASJC Scopus subject areas

  • Genetics


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