Coordinate regulation of G- and C strand length during new telomere synthesis

Mol Biol Cell. 1997 Nov;8(11):2145-55. doi: 10.1091/mbc.8.11.2145.


We have used the ciliate Euplotes to study the role of DNA polymerase in telomeric C strand synthesis. Euplotes provides a unique opportunity to study C strand synthesis without the complication of simultaneous DNA replication because millions of new telomeres are made at a stage in the life cycle when no general DNA replication takes place. Previously we showed that the C-strands of newly synthesized telomeres have a precisely controlled length while the G-strands are more heterogeneous. This finding suggested that, although synthesis of the G-strand (by telomerase) is the first step in telomere addition, a major regulatory step occurs during subsequent C strand synthesis. We have now examined whether G- and C strand synthesis might be regulated coordinately rather than by two independent mechanisms. We accomplished this by determining what happens to G- and C strand length if C strand synthesis is partially inhibited by aphidicolin. Aphidicolin treatment caused a general lengthening of the G-strands and a large increase in C strand heterogeneity. This concomitant change in both the G- and C strand length indicates that synthesis of the two strands is coordinated. Since aphidicolin is a very specific inhibitor of DNA pol alpha and pol delta, our results suggest that this coordinate length regulation is mediated by DNA polymerase.

Publication types

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

MeSH terms

  • Animals
  • Aphidicolin / pharmacology
  • Base Composition
  • Cloning, Molecular
  • Cytosine
  • DNA Replication / drug effects
  • DNA, Protozoan / biosynthesis*
  • DNA, Protozoan / chemistry
  • DNA-Directed DNA Polymerase / physiology
  • Enzyme Inhibitors / pharmacology
  • Euplotes / cytology
  • Euplotes / genetics*
  • Guanine
  • Nucleic Acid Synthesis Inhibitors
  • Sequence Analysis, DNA
  • Telomerase / metabolism
  • Telomere / chemistry
  • Telomere / metabolism*


  • DNA, Protozoan
  • Enzyme Inhibitors
  • Nucleic Acid Synthesis Inhibitors
  • Aphidicolin
  • Guanine
  • Cytosine
  • Telomerase
  • DNA-Directed DNA Polymerase