Ide S~Kobayashi T, 2013

Pubmed ID 23593017
Title Rtt109 prevents hyper-amplification of ribosomal RNA genes through histone modification in budding yeast.
Authors Satoru Ide, Kimiko Saka, Takehiko Kobayashi
Abstract The genes encoding ribosomal RNA are the most abundant in the eukaryotic genome. They reside in tandem repetitive clusters, in some cases totaling hundreds of copies. Due to their repetitive structure, ribosomal RNA genes (rDNA) are easily lost by recombination events within the repeated cluster. We previously identified a unique gene amplification system driven by unequal sister-chromatid recombination during DNA replication. The system compensates for such copy number losses, thus maintaining proper copy number. Here, through a genome-wide screen for genes regulating rDNA copy number, we found that the rtt109 mutant exhibited a hyper-amplification phenotype (∼3 times greater than the wild-type level). RTT109 encodes an acetyl transferase that acetylates lysine 56 of histone H3 and which functions in replication-coupled nucleosome assembly. Relative to unequal sister-chromatid recombination-based amplification (∼1 copy/cell division), the rate of the hyper-amplification in the rtt109 mutant was extremely high (>100 copies/cell division). Cohesin dissociation that promotes unequal sister-chromatid recombination was not observed in this mutant. During hyper-amplification, production level of extra-chromosomal rDNA circles (ERC) by intra-chromosomal recombination in the rDNA was reduced. Interestingly, during amplification, a plasmid containing an rDNA unit integrated into the rDNA as a tandem array. These results support the idea that tandem DNA arrays are produced and incorporated through rolling-circle-type replication. We propose that, in the rtt109 mutant, rDNA hyper-amplification is caused by uncontrolled rolling-circle-type replication.
Citation PLoS Genet. 2013; 9:e1003410


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Paper Phenotype Condition Medium Collection Tested mutants Data Details
Ide S~Kobayashi T, 2013 rDNA copy number standard YPD hap a ~4,800 Discrete

Curation history

Tested strains

Feb. 8, 2019 To request.


Feb. 8, 2019 Waiting for tested.