Homing Endonucleases and the Yeast Mitochondrial ω Locus — A Historical Perspective

Dujon, Bernard

doi:10.1007/3-540-29474-0_2

Cited by 8 publications

(6 citation statements)

References 79 publications

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“…Consequently, the accidental encountering of intron‐plus and intron‐minus mitochondrial alleles in a heteroplasmic cell (after a cross between different strains) triggers a gene‐drive mechanism designated intron homing (Figure b). This mechanism, based on double‐strand break‐induced homologous recombination, not only converts intron‐less alleles into intron‐plus ones (propagating the intron) but also extends the genetic conversion over flanking exon sequences (see Dujon, ). It is precisely this last property (at the origin of mobile intron discovery, see Figure ) that makes Group I introns drivers of mitochondrial allele inheritance, able to act on the genetic diversity of their host.…”

Section: Invasive Genetic Elementsmentioning

confidence: 99%

Mitochondrial genetics revisited

Dujon

2020

Yeast

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Mitochondrial genetics started decades ago with the discovery of yeast mutants that ignored the Mendelian rules of inheritance. Today, the many known DNA sequences of this second eukaryotic genome illustrate its eccentricity in terms of informational content and functional organisation, suggesting a yet incomplete understanding of its evolution. The hereditary transmission of mitochondrial alleles relies on complex mixes of molecular and cellular mechanisms in which recombination and limited sampling, two sources of rapid genetic changes, play central roles. It is also under the influence of invasive genetic elements whose inconstant distribution in mitochondrial genomes suggests rapid turnovers in evolving populations. This susceptibility to changes contrasts with the development of specific functional interactions between the mitochondrial and nuclear genetic compartments, a trend that is prone to limit the genetic exchanges between distinct lineages. It is perhaps this opposition and the discordant inheritance between mitochondrial and nuclear genomes that best explain the maintenance of a second genome and a second independent protein synthesising machinery in eukaryotic cells.

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Section: Invasive Genetic Elementsmentioning

confidence: 99%

Mitochondrial genetics revisited

Dujon

2020

Yeast

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“…The catalytic motifs of HO, I-SceI, and VDE are related, such that each gives rise to a 4-base 3′ overhang [72, 73]. The sequences of the recognition sites are quite distinct, however, although each is asymmetric and long, giving rise to the term “meganuclease”.…”

Section: Meganucleases Used To Study Dsb Repairmentioning

confidence: 99%

The democratization of gene editing: Insights from site-specific cleavage and double-strand break repair

2016

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DNA double-strand breaks (DSBs) are dangerous lesions that if not properly repaired can lead to genomic change or cell death. Organisms have developed several pathways and have many factors devoted to repairing DSBs, which broadly occur by homologous recombination that relies on an identical or homologous sequence to template repair, or nonhomologous end-joining. Much of our understanding of these repair mechanisms has come from the study of induced DNA cleavage by site-specific endonucleases. In addition to their biological role, these cellular pathways can be co-opted for gene editing to study gene function or for gene therapy or other applications. While the first gene editing experiments were done more than 20 years ago, the recent discovery of RNA-guided endonucleases has simplified approaches developed over the years to make gene editing an approach that is available to the entire biomedical research community. Here, we review DSB repair mechanisms and site-specific cleavage systems that have provided insight into these mechanisms and led to the current gene editing revolution.

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“…For most cytoplasmic components (including mitochondria and chloroplasts), inheritance tends to be uniparental, ensuring uniparental inheritance of HEGs and their intron partners. However, so-called "super-mendelian" inheritance has been noted in uni-or bi-parental inheritance systems in yeasts where introns can spread to the progeny efficiently due to the potential of mitochondria originating from the two mating types fusing and introns homing into intron-less alleles [123]. HEs catalyze intron mobility in organelles and there are indications that nuclear genes may impact the mobility and possible inheritance of mobile introns.…”

Section: Intron-encoded Proteins In Guiding Intron Mobility and Multifunctional Rolesmentioning

confidence: 99%

Organellar Introns in Fungi, Algae, and Plants

Mukhopadhyay

Hausner

2021

Cells

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Introns are ubiquitous in eukaryotic genomes and have long been considered as ‘junk RNA’ but the huge energy expenditure in their transcription, removal, and degradation indicate that they may have functional significance and can offer evolutionary advantages. In fungi, plants and algae introns make a significant contribution to the size of the organellar genomes. Organellar introns are classified as catalytic self-splicing introns that can be categorized as either Group I or Group II introns. There are some biases, with Group I introns being more frequently encountered in fungal mitochondrial genomes, whereas among plants Group II introns dominate within the mitochondrial and chloroplast genomes. Organellar introns can encode a variety of proteins, such as maturases, homing endonucleases, reverse transcriptases, and, in some cases, ribosomal proteins, along with other novel open reading frames. Although organellar introns are viewed to be ribozymes, they do interact with various intron- or nuclear genome-encoded protein factors that assist in the intron RNA to fold into competent splicing structures, or facilitate the turn-over of intron RNAs to prevent reverse splicing. Organellar introns are also known to be involved in non-canonical splicing, such as backsplicing and trans-splicing which can result in novel splicing products or, in some instances, compensate for the fragmentation of genes by recombination events. In organellar genomes, Group I and II introns may exist in nested intronic arrangements, such as introns within introns, referred to as twintrons, where splicing of the external intron may be dependent on splicing of the internal intron. These nested or complex introns, with two or three-component intron modules, are being explored as platforms for alternative splicing and their possible function as molecular switches for modulating gene expression which could be potentially applied towards heterologous gene expression. This review explores recent findings on organellar Group I and II introns, focusing on splicing and mobility mechanisms aided by associated intron/nuclear encoded proteins and their potential roles in organellar gene expression and cross talk between nuclear and organellar genomes. Potential application for these types of elements in biotechnology are also discussed.

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Homing Endonucleases and the Yeast Mitochondrial ω Locus — A Historical Perspective

Cited by 8 publications

References 79 publications

Mitochondrial genetics revisited

Mitochondrial genetics revisited

The democratization of gene editing: Insights from site-specific cleavage and double-strand break repair

Organellar Introns in Fungi, Algae, and Plants

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