The Tetrahymena p80/p95 complex is required for proper telomere length maintenance and micronuclear genome stability

Mol Cell. 2000 Oct;6(4):827-37. doi: 10.1016/s1097-2765(05)00078-x.


The telomerase enzyme adds simple sequence repeats to chromosome ends. Telomerases share two essential subunits, telomerase RNA and telomerase reverse transcriptase, that associate with species-specific proteins of predominantly unknown functions. The Tetrahymena p80/p95 complex can coimmunopurify active telomerase from cell extract, and recombinant p80/p95 can interact directly with telomerase RNA and single-stranded telomeric DNA in vitro. Here, we test the functions of p80/p95 in vivo. Surprisingly, telomerase RNA accumulation and telomerase activity in cell extract are unaffected by loss of the genes encoding p80/p95. However, in the absence of p80/p95, telomeres become elongated in both macronuclei and micronuclei. Micronuclear chromosome maintenance is also compromised. These findings suggest that p80/p95 functions to maintain appropriate telomere length and micronuclear genomic stability but does so in a manner different than previously anticipated.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Gene Deletion
  • Genome, Protozoan*
  • Micronucleus, Germline / genetics*
  • Phenotype
  • Protein Subunits
  • Protozoan Proteins / metabolism*
  • RNA, Protozoan / genetics
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / metabolism*
  • Recombinant Proteins / metabolism
  • Telomerase / metabolism*
  • Telomere / genetics*
  • Telomere-Binding Proteins*
  • Tetrahymena / enzymology
  • Tetrahymena / genetics*
  • Tetrahymena / growth & development
  • Transformation, Genetic


  • Carrier Proteins
  • Protein Subunits
  • Protozoan Proteins
  • RNA, Protozoan
  • RNA-Binding Proteins
  • Recombinant Proteins
  • Telomere-Binding Proteins
  • p95 protein, Tetrahymena
  • Telomerase
  • telomerase p80 protein, Tetrahymena