Abundance of Ribosomal RNA Gene Copies Maintains Genome Integrity

  title={Abundance of Ribosomal RNA Gene Copies Maintains Genome Integrity},
  author={Satoru Ide and Takaaki Miyazaki and Hisaji Maki and Takehiko Kobayashi},
  pages={693 - 696}
Protective Abundance Massively repeated sequences are generally dangerous to genomes because they promote recombination and, potentially, genome instability. Eukaryotic ribosomal RNA genes (rDNA), which are highly transcribed, are organized into large arrays of repeats and have a system that actively maintains these large arrays. In getting to the bottom of this apparent contradiction, Ide et al. (p. 693) found that reducing the number of rDNA repeats in yeast resulted in a marked sensitivity… 

Ribosomal DNA instability and genome adaptability

Evidence uncovering mechanisms of regulation of instability and copy number variation at the rDNA and their role in adaptation to the environment is reviewed, which could serve to understand the basic principles governing the behavior of other tandem repeats and their roles in shaping the genome.

DNA replication stress restricts ribosomal DNA copy number

The data suggest that a reduction in rDNA copy number may indicate a history of DNA replication stress, and that rDNA array size could serve as a diagnostic marker for replication Stress, and begin to suggest the selective pressures that combine to yield a “normal” r DNA copy number.

Regulation of ribosomal RNA gene copy number and its role in modulating genome integrity and evolutionary adaptability in yeast

A new aspect of the rRNA gene repeat (called rDNA) is introduced as a center of maintenance of genome integrity and its contribution to evolution is discussed.

Genome instability: The more, the merrier

  • R. David
  • Biology
    Nature Reviews Molecular Cell Biology
  • 2010
It is shown that multiple copies of rDNA are required for efficient HR repair during replication because they facilitate the association of sister chromatids with condensin during DNA replication.

Rtt109 Prevents Hyper-Amplification of Ribosomal RNA Genes through Histone Modification in Budding Yeast

The results support the idea that tandem DNA arrays are produced and incorporated through rolling-circle-type replication, and propose that, in the rtt109 mutant, rDNA hyper-amplification is caused by uncontrolled rolling- circle- type replication.

Genome Instability of Repetitive Sequence: Lesson from the Ribosomal RNA Gene Repeat

This review will introduce the unique mechanisms by which the rDNA repetitive region and its physiological functions are maintained.

Rejuvenation of ribosomal RNA gene repeats at the nuclear pore

The possible contribution of nuclear pores to the asymmetric distribution of damaged rDNA between mother and daughter cells as well as its possible impact on aging/rejuvenation are proposed.

Ribosomal RNA gene repeats associate with the nuclear pore complex for maintenance after DNA damage

It is demonstrated that the conserved protein kinase Tel1 maintains rDNA stability after replication fork arrest, and this findings suggest that rDNA-nuclear pore association is due to a replication fork block and subsequent DSB.

Gene dosage compensation of rRNA transcript levels in Arabidopsis thaliana lines with reduced ribosomal gene copy number

Gene dosage compensation of rRNA transcript levels was associated with reduction of silencing histone marks at rDNA loci and altered Nucleolar Organiser Region 2 organization, and overall genome integrity of LCN lines appears unaffected, a chromosome segmental duplication occurred in one of the lines.



Recombination Regulation by Transcription-Induced Cohesin Dissociation in rDNA Repeats

It is shown that amplification is dependent on transcription from a noncoding bidirectional promoter (E-pro) within the rDNA spacer, which stimulates the dissociation of cohesin, a DNA binding protein complex that suppresses sister-chromatid-based changes in rDNA copy number.

RNA polymerase I transcription obstructs condensin association with 35S rRNA coding regions and can cause contraction of long repeat in Saccharomyces cerevisiae

It is shown that RNA polymerase I transcription interferes with condensin association with 35S rRNA coding regions in fob1 cells and causes dramatic contraction of rDNA repeat in the fOB1 Condensin double mutant.

Abnormality in Initiation Program of DNA Replication Is Monitored by the Highly Repetitive rRNA Gene Array on Chromosome XII in Budding Yeast

It is reported that DNA lesions in the orc mutants are induced much more quickly and frequently within the rRNA gene (rDNA) locus than at other chromosomal loci upon temperature shift, suggesting that the rDNA locus primarily signals abnormalities in the initiation program to the DNA damage checkpoint and that the RDNA copy number modulates the sensitivity of this monitoring function.

Genetics of bacterial ribosomes.

In Exponentially Growing Saccharomyces cerevisiae Cells, rRNA Synthesis Is Determined by the Summed RNA Polymerase I Loading Rate Rather than by the Number of Active Genes

It is shown that overall initiation rate, and not the number of active genes, determines rRNA transcription rate during exponential growth in yeast.

Identification of cis-acting sites for condensin loading onto budding yeast chromosomes.

Analysis of condensin binding to budding yeast chromosomes using high-resolution oligonucleotide tiling arrays reveals that TFIIIC-binding sites constitute a hitherto unknown chromosomal feature with important implications for chromosome architecture during both interphase and mitosis.

A genome-wide screen for methyl methanesulfonate-sensitive mutants reveals genes required for S phase progression in the presence of DNA damage

A systematic screen of the set of viable Saccharomyces cerevisiae haploid gene deletion mutants is performed and 103 genes whose deletion causes sensitivity to the DNA-damaging agent methyl methanesulfonate are identified, including a subset of genes that show a specific MMS response.