A sequence-dependent exonuclease activity from Tetrahymena thermophila

Hui I.Kao Tom, Carol W. Greider

Research output: Contribution to journalArticlepeer-review


Background. Telomere function requires a highly conserved G rich 3′- overhang. This structure is formed by 5′-resection of the C-rich telomere strand. However, while many nucleases have been suggested to play a role in processing, it is not yet clear which nucleases carry out this 5′-resection. Results. We used biochemical purification to identify a sequence-dependent exonuclease activity in Tetrahymena thermophila cell extracts. The nuclease activity showed specificity for 5′-ends containing AA or AC sequences, unlike Exo1, which showed sequence-independent cleavage. The Tetrahymena nuclease was active on both phosphorylated and unphosphorylated substrates whereas Exo1 requires a 5′-phosphate for cleavage. Conclusions. The specificities of the enzyme indicate that this novel Tetrahymena exonuclease is distinct from Exo1 and has properties required for 3′-overhang formations at telomeres.

Original languageEnglish (US)
Article number45
JournalBMC Biochemistry
Issue number1
StatePublished - 2010

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology


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