CTD kinase I is required for the integrity of the rDNA tandem array

Nucleic Acids Res. 2006;34(17):4996-5006. doi: 10.1093/nar/gkl493. Epub 2006 Sep 19.


The genomic stability of the rDNA tandem array is tightly controlled to allow sequence homogenization and to prevent deleterious rearrangements. In this report, we show that the absence of the yeast CTD kinase I (CTDK-I) complex in null mutant strains leads to a decrease in the number of tandem rDNA repeats. Reintroduction of the missing gene induces an increase of rDNA repeats to reach a copy number similar to that of the original strain. Interestingly, while expansion is dependent on Fob1, a protein required for replication fork blocking activity in rDNA, contraction occurs in the absence of Fob1. Furthermore, silencing of class II genes at the rDNA, a process connected to rDNA stability, is not affected. Ctk1, the kinase subunit of the CTDK-I complex is involved in various steps of mRNA synthesis. In addition, we have recently shown that Ctk1 is also implicated in rRNA synthesis. The results suggest that the RNA polymerase I transcription defect occurring in a ctk1 mutant strain causes rDNA contraction.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Cycle Proteins / metabolism
  • Chromosomal Proteins, Non-Histone / metabolism
  • DNA, Ribosomal / analysis
  • DNA, Ribosomal / genetics*
  • DNA-Binding Proteins / physiology
  • Gene Deletion
  • Gene Silencing
  • Genes, rRNA*
  • Multigene Family
  • Nuclear Proteins / metabolism
  • Protein Kinases / genetics
  • Protein Kinases / physiology*
  • RNA Polymerase I / metabolism
  • Saccharomyces cerevisiae / enzymology*
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / physiology*
  • Transcription, Genetic


  • CTDK-I protein complex, S cerevisiae
  • Cell Cycle Proteins
  • Chromosomal Proteins, Non-Histone
  • DNA, Ribosomal
  • DNA-Binding Proteins
  • FOB1 protein, S cerevisiae
  • Nuclear Proteins
  • Saccharomyces cerevisiae Proteins
  • cohesins
  • Protein Kinases
  • RNA Polymerase I