A positive role for yeast extrachromosomal rDNA circles?

Poole, Anthony M.; Kobayashi, Takehiko; Ganley, Austen R. D.

doi:10.1002/bies.201200037

Cited by 18 publications

(16 citation statements)

References 33 publications

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“…Proteins like Fap7, which were identified as a protein involved in oxidative stress, have been recently shown to be involved in 40S biogenesis (53, 54). Interestingly, the antisense strand of 25S rRNA also carries a mitochondrial protein Tar1, which is the most abundant protein-coding gene in yeast and has been reported to be essential for the mitochondrial function (55). Although the clue why this results in increased hydrogen peroxide sensitivity remains still obscure, the interference of ribosome biogenesis and ribosome function with oxidative stress becomes more and more obvious, and future studies are required to elucidate this phenomenon.…”

Section: Discussionmentioning

confidence: 99%

Identification of a novel methyltransferase, Bmt2, responsible for the N-1-methyl-adenosine base modification of 25S rRNA in Saccharomyces cerevisiae

Sharma

Watzinger

Kötter

et al. 2013

Nucleic Acids Research

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The 25S rRNA of yeast contains several base modifications in the functionally important regions. The enzymes responsible for most of these base modifications remained unknown. Recently, we identified Rrp8 as a methyltransferase involved in m1A645 modification of 25S rRNA. Here, we discovered a previously uncharacterized gene YBR141C to be responsible for second m1A2142 modification of helix 65 of 25S rRNA. The gene was identified by reversed phase–HPLC screening of all deletion mutants of putative RNA methyltransferase and was confirmed by gene complementation and phenotypic characterization. Because of the function of its encoded protein, YBR141C was named BMT2 (base methyltransferase of 25S RNA). Helix 65 belongs to domain IV, which accounts for most of the intersubunit surface of the large subunit. The 3D structure prediction of Bmt2 supported it to be an Ado Met methyltransferase belonging to Rossmann fold superfamily. In addition, we demonstrated that the substitution of G180R in the S-adenosyl-l-methionine–binding motif drastically reduces the catalytic function of the protein in vivo. Furthermore, we analysed the significance of m1A2142 modification in ribosome synthesis and translation. Intriguingly, the loss of m1A2142 modification confers anisomycin and peroxide sensitivity to the cells. Our results underline the importance of RNA modifications in cellular physiology.

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Section: Discussionmentioning

confidence: 99%

Identification of a novel methyltransferase, Bmt2, responsible for the N-1-methyl-adenosine base modification of 25S rRNA in Saccharomyces cerevisiae

Sharma

Watzinger

Kötter

et al. 2013

Nucleic Acids Research

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“…It has been shown experimentally that rDNA units can “pop out” of the S. cerevisiae rDNA array by intramolecular recombination between different units in the array, forming a 9.1-kb circular DNA molecule or multimers of this structure (Sinclair and Guarente 1997; Poole et al 2012). These extrachromosomal rDNA circles (ERCs) are capable of replication because each rDNA unit contains an origin of replication.…”

Section: Discussionmentioning

confidence: 99%

Evolutionary Mobility of the Ribosomal DNA Array in Yeasts

Proux‐Wéra¹,

Byrne²,

Wolfe³

2013

Genome Biology and Evolution

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The ribosomal DNA (rDNA) of eukaryotes is organized as large tandem arrays. Here, we compare the genomic locations of rDNA among yeast species and show that, despite its huge size (>1 Mb), the rDNA array has moved around the genome several times within the family Saccharomycetaceae. We identify an ancestral, nontelomeric, rDNA site that is conserved across many species including Saccharomyces cerevisiae. Within the genus Lachancea, however, the rDNA apparently transposed from the ancestral site to a new site internal to a different chromosome, becoming inserted into a short intergenic region beside a tRNA gene. In at least four other yeast lineages, the rDNA moved from the ancestral site to telomeric locations. Remarkably, both the ancestral rDNA site and the new site in Lachancea are adjacent to protein-coding genes whose products maintain the specialized chromatin structure of rDNA (HMO1 and CDC14, respectively). In almost every case where the rDNA was lost from the ancestral site, the entire array disappeared without any other rearrangements in the region, leaving just an intergenic spacer of less than 2 kb. The mechanism by which this large and complex locus moves around the genome is unknown, but we speculate that it may involve the formation of double-strand DNA breaks by Fob1 protein or the formation of extrachromosomal rDNA circles.

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“…It has been proposed that activation of the retrograde response by loss of mtDNA might require more Rtg2 for the transduction of the retrograde response signaling, leading to less repression of ERC formation (Jazwinski, 2005). In addition, it was proposed that ERCs signal back to the mitochondria via Tar1, a protein that is encoded on the antisense strand of the rDNA repeat and localizes to the mitochondria (Poole et al, 2012). However, neither the function of Tar1 nor whether the amount of ERCs influences the levels of Tar1 is known.…”

Section: Retrograde Responsementioning

confidence: 99%

Budding yeast as a model organism to study the effects of age

2014

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Although a budding yeast culture can be propagated eternally, individual yeast cells age and eventually die. The detailed knowledge of this unicellular eukaryotic species as well as the powerful tools developed to study its physiology makes budding yeast an ideal model organism to study the mechanisms involved in aging. Considering both detrimental and positive aspects of age, we review changes occurring during aging both at the whole-cell level and at the intracellular level. The possible mechanisms allowing old cells to produce rejuvenated progeny are described in terms of accumulation and inheritance of aging factors. Based on the dynamic changes associated with age, we distinguish different stages of age: early age, during which changes do not impair cell growth; intermediate age, during which aging factors start to accumulate; and late age, which corresponds to the last divisions before death. For each aging factor, we examine its asymmetric segregation and whether it plays a causal role in aging. Using the example of caloric restriction, we describe how the aging process can be modulated at different levels and how changes in different organelles might interplay with each other. Finally, we discuss the beneficial aspects that might be associated with age.

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A positive role for yeast extrachromosomal rDNA circles?

Cited by 18 publications

References 33 publications

Identification of a novel methyltransferase, Bmt2, responsible for the N-1-methyl-adenosine base modification of 25S rRNA in Saccharomyces cerevisiae

Identification of a novel methyltransferase, Bmt2, responsible for the N-1-methyl-adenosine base modification of 25S rRNA in Saccharomyces cerevisiae

Evolutionary Mobility of the Ribosomal DNA Array in Yeasts

Budding yeast as a model organism to study the effects of age

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