Circular rDNA Replicons Persist in Tetrahymena thermophila Transformants Synthesizing GGGGTC Telomeric Repeats

DANIEL P. ROMERO, ELIZABETH H. BLACKBURN

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Site‐directed mutagenesis of the telomerase RNA from Tetrahymena thermophila was used previously to demonstrate the templating function of a sequence within this RNA; this sequence specifies the sequence of telomeric DNA in vivo. The possible functional importance of a phylogenetically conserved nucleotide outside the telomerase RNA template region was investigated by a similar experimental approach. The telomerase RNA gene was altered by site‐directed mutagenesis, cloned in a circular selectable transformation vector consisting of an rRNA gene carrying a selectable drug resistance marker, and introduced into macronuclei of vegetatively dividing Tetrahymena thermophila by microinjection. Changing an invariant A to U at position 16 of the telomerase RNA (A16U) had no effect detectable by phenotype on telomerase function in vivo. However these experiments showed that a telomerase template alteration that dictates the synthesis of the mutant telomeric DNA sequence GGGGTC leads to a profound change in the population of rDNA replicons. The addition of GGGGTC mutant repeats leads to selective pressure for the loss of high copy linear rDNA, and the rRNA genes are maintained in the form of the circular rDNA replicons introduced during transformation.

Original languageEnglish (US)
Pages (from-to)32-43
Number of pages12
JournalJournal of Eukaryotic Microbiology
Volume42
Issue number1
DOIs
StatePublished - Jan 1995

Keywords

  • Ribosomal DNA replication
  • telomerase
  • telomerase RNA
  • telomeres

Fingerprint Dive into the research topics of 'Circular rDNA Replicons Persist in Tetrahymena thermophila Transformants Synthesizing GGGGTC Telomeric Repeats'. Together they form a unique fingerprint.

Cite this