Homologous recombination mediated by two palindromic repeated sequences in the mitochondrial genome of Oryza

1995 ◽  
Vol 91 (1) ◽  
pp. 1-8 ◽  
Author(s):  
N. Nakazono ◽  
A. Kanno ◽  
N. Tsutsumi ◽  
A. Hirai
Keyword(s):  
Homologous Recombination ◽  
Mitochondrial Genome ◽  
Repeated Sequences ◽  
Palindromic Repeated Sequences

scholarly journals Mitochondrial Genome Rearrangements in Glomus Species Triggered by Homologous Recombination between Distinct mtDNA Haplotypes

2013 ◽  
Vol 5 (9) ◽  
pp. 1628-1643 ◽  
Author(s):  
Denis Beaudet ◽  
Yves Terrat ◽  
Sébastien Halary ◽  
Ivan Enrique de la Providencia ◽  
Mohamed Hijri
Keyword(s):  
Homologous Recombination ◽  
Mitochondrial Genome ◽  
Genome Rearrangements ◽  
Mtdna Haplotypes ◽  
Glomus Species

scholarly journals The M26 Hotspot of Schizosaccharomyces pombe Stimulates Meiotic Ectopic Recombination and Chromosomal Rearrangements

Genetics ◽  
1998 ◽  
Vol 149 (3) ◽  
pp. 1191-1204 ◽  
Author(s):  
Jeffrey B Virgin ◽  
Jeffrey P Bailey
Keyword(s):  
Homologous Recombination ◽  
Schizosaccharomyces Pombe ◽  
Dna Sequences ◽  
Chromosomal Rearrangements ◽  
Low Frequency ◽  
Repeated Sequences ◽  
Crossing Over ◽  
Ectopic Recombination ◽  
Recombination Hotspots ◽  
Integration Sites

Abstract Homologous recombination is increased during meiosis between DNA sequences at the same chromosomal position (allelic recombination) and at different chromosomal positions (ectopic recombination). Recombination hotspots are important elements in controlling meiotic allelic recombination. We have used artificially dispersed copies of the ade6 gene in Schizosaccharomyces pombe to study hotspot activity in meiotic ectopic recombination. Ectopic recombination was reduced 10–1000-fold relative to allelic recombination, and was similar to the low frequency of ectopic recombination between naturally repeated sequences in S. pombe. The M26 hotspot was active in ectopic recombination in some, but not all, integration sites, with the same pattern of activity and inactivity in ectopic and allelic recombination. Crossing over in ectopic recombination, resulting in chromosomal rearrangements, was associated with 35–60% of recombination events and was stimulated 12-fold by M26. These results suggest overlap in the mechanisms of ectopic and allelic recombination and indicate that hotspots can stimulate chromosomal rearrangements.

scholarly journals Strategies and difficulties in assembling highly recombinogenic plant organelle genomes: a case study

2015 ◽  
Author(s):  
Concita Cantarella ◽  
Rachele Tamburino ◽  
Nunzia Scotti ◽  
Teodoro Cardi ◽  
Nunzio D'Agostino
Keyword(s):  
Mitochondrial Dna ◽  
Mitochondrial Genome ◽  
De Novo ◽  
Sequence Data ◽  
Repeated Sequences ◽  
Read Length ◽  
Plant Mitochondrial Genome ◽  
Sequencing Platform ◽  
Organelle Genomes ◽  
Long Read

Mitochondrial genomes in plants are larger and more complex than in other eukaryotes due to their recombinogenic nature as widely demonstrated. The mitochondrial DNA (mtDNA) is usually represented as a single circular map, the so-called master molecule. This molecule includes repeated sequences, some of which are able to recombine, generating sub-genomic molecules in various amounts, depending on the balance between their recombination and replication rates. Recent advances in DNA sequencing technology gave a huge boost to plant mitochondrial genome projects. Conventional approaches to mitochondrial genome sequencing involve extraction and enrichment of mitochondrial DNA, cloning, and sequencing. Large repeats and the dynamic mitochondrial genome organization complicate de novo sequence assembly from short reads. The PacBio RS long-read sequencing platform offers the promise of increased read length and unbiased genome coverage and thus the potential to produce genome sequence data of a finished quality (fewer gaps and longer contigs). However, recently published articles revealed that PacBio sequencing is still not sufficient to address mtDNA assembly-related issues. Here we present a preliminary hybrid assembly of a potato mtDNA based on both PacBio and Illumina reads and debate the strategies and obstacles in assembling genomes containing repeated sequences that are recombinationally active and serve as a constant source of rearrangements.

The plant mitochondrial genome: homologous recombination as a mechanism for generating heterogeneity

1988 ◽  
Vol 319 (1193) ◽  
pp. 149-163 ◽  
Keyword(s):  
Mitochondrial Dna ◽  
Homologous Recombination ◽  
Mitochondrial Genome ◽  
Higher Plants ◽  
Genome Structure ◽  
Rapid Evolution ◽  
Mitochondrial Genomes ◽  
Base Sequence ◽  
Plant Mitochondrial Genome ◽  
Organelle Genomes

The mitochondrial genomes of higher plants are among the largest and most complex organelle genomes described. They are generally multicircular or partly linear; in some species, extrachromosomal plasmids are present. It is proposed that inter- and intramolecular homologous recombination can account for the diversity of the observed genome organizations. The ability of mitochondria to fuse establishes a panmictic mitochondrial DNA population which is in recombinational equilibrium. It is suggested that this suppresses the base mutation rate, and unequal partitioning of the cytoplasm during cell division can lead to the rapid evolution of mitochondrial genome structure. This contrasts with the observed rates of base-sequence and genome evolution in chloroplasts. This difference can be accounted for solely by the inability of chloroplasts to fuse, thereby preventing chloroplast genome panmixis.

scholarly journals Homologous recombination changes the context of Cytochrome b transcription in the mitochondrial genome of Silene vulgaris KRA

2018 ◽  
Author(s):  
Helena Štorchová ◽  
James D. Stone ◽  
Daniel B. Sloan ◽  
Oushadee Abeyawardana ◽  
Karel Müller ◽  
...  
Keyword(s):  
Homologous Recombination ◽  
Mitochondrial Genome ◽  
Rna Editing ◽  
Cytochrome B ◽  
Mitochondrial Genes ◽  
Mitochondrial Genomes ◽  
Silene Vulgaris ◽  
Fertility Restorer ◽  
Restorer Genes ◽  
Fertility Restorer Genes

AbstractBackgroundSilene vulgaris (bladder campion) is a gynodioecious species existing as two genders – male-sterile females and hermaphrodites. Cytoplasmic male sterility (CMS) is generally encoded by mitochondrial genes, which interact with nuclear fertility restorer genes. Mitochondrial genomes of this species vary in DNA sequence, gene order and gene content. Multiple CMS genes are expected to exist in S. vulgaris, but little is known about their molecular identity.ResultsWe assembled the complete mitochondrial genome from the haplotype KRA of S. vulgaris. It consists of five chromosomes, two of which recombine with each other. Two small non-recombining chromosomes exist in linear, supercoiled and relaxed circle forms. We compared the mitochondrial transcriptomes from females and hermaphrodites and confirmed the differentially expressed chimeric gene bobt as the strongest CMS candidate gene in S. vulgaris KRA. The chimeric gene bobt is co-transcribed with the Cytochrome b (cob) gene in some genomic configurations. The co-transcription of a CMS factor with an essential gene may constrain transcription inhibition as a mechanism for fertility restoration because of the need to maintain appropriate production of the necessary protein. Homologous recombination places the gene cob outside the control of bobt, which allows for the suppression the CMS gene by the fertility restorer genes. In addition, by analyzing RNA editing, we found the loss of three editing sites in the KRA mitochondrial genome and identified four sites with highly distinct editing rates between KRA and another S. vulgaris haplotypes (KOV). Three of these highly differentially edited sites were located in the transport membrane protein B (mttB) gene. They resulted in differences in MttB protein sequences between haplotypes despite completely identical gene sequences.ConclusionsFrequent homologous recombination events that are widespread in plant mitochondrial genomes may change chromosomal configurations and also the control of gene transcription including CMS gene expression. Posttranscriptional processes, e.g RNA editing shall be evaluated in evolutionary and co-evolutionary studies of mitochondrial genes, because they may change protein composition despite the sequence identity of the respective genes. The investigation of natural populations of wild species such as S. vulgaris are necessary to reveal important aspects of CMS missed in domesticated crops, the traditional focus of the CMS studies.

Involvement of cDNA in homologous recombination between Ty elements in Saccharomyces cerevisiae

1992 ◽  
Vol 12 (4) ◽  
pp. 1613-1620
Author(s):  
C Melamed ◽  
Y Nevo ◽  
M Kupiec
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Homologous Recombination ◽  
Reverse Transcriptase ◽  
Gene Conversion ◽  
Reverse Transcription ◽  
Repeated Sequences ◽  
Homologous Gene ◽  
Ty Elements ◽  
Low Level ◽  
Ty Element

Strains carrying a marked Ty element (TyUra) in the LYS2 locus were transformed with plasmids bearing a differently marked Ty1 element (Ty1Neo) under the control of the GAL promoter. When these strains were grown in glucose, a low level of gene conversion events involving TyUra was detected. Upon growth on galactose an increase in the rate of gene conversion was seen. This homologous recombination is not the consequence of increased levels of transposition. When an intron-containing fragment was inserted into Ty1Neo, some of the convertants had the intron removed, implying an RNA intermediate. Mutations that affect reverse transcriptase or reverse transcription of Ty1Neo greatly reduce the induction of recombination in galactose. Thus, Ty cDNA is involved in homologous gene conversion with chromosomal copies of Ty elements. Our results have implications about the way families of repeated sequences retain homogeneity throughout evolution.

scholarly journals Integration of a vector containing a repetitive LINE-1 element in the human genome.

1994 ◽  
Vol 14 (10) ◽  
pp. 6689-6695 ◽  
Author(s):  
M Richard ◽  
A Belmaaza ◽  
N Gusew ◽  
J C Wallenburg ◽  
P Chartrand
Keyword(s):  
Homologous Recombination ◽  
Human Genome ◽  
Mammalian Cells ◽  
Gene Families ◽  
Repeated Sequences ◽  
Mammalian Genomes ◽  
L1 Element ◽  
Multicopy Genes ◽  
The Stability ◽  
Reciprocal Process

Mammalian cells contain numerous nonallelic repeated sequences, such as multicopy genes, gene families, and repeated elements. One common feature of nonallelic repeated sequences is that they are homeologous (not perfectly identical). Our laboratory has been studying recombination between homeologous sequences by using LINE-1 (L1) elements as substrates. We showed previously that an exogenous L1 element could readily acquire endogenous L1 sequences by nonreciprocal homologous recombination. In the study presented here, we have investigated the propensity of exogenous L1 elements to be involved in a reciprocal process, namely, crossing-overs. This would result in the integration of the exogenous L1 element into an endogenous L1 element. Of over 400 distinct integration events analyzed, only 2% involved homologous recombination between exogenous and endogenous L1 elements. These homologous recombination events were imprecise, with the integrated vector being flanked by one homologous and one illegitimate junction. This type of structure is not consistent with classical crossing-overs that would result in two homologous junctions but rather is consistent with one-sided homologous recombination followed by illegitimate integration. Contrary to what has been found for reciprocal homologous integration, the degree of homology between the exogenous and endogenous L1 elements did not seem to play an important role in the choice of recombination partners. These results suggest that although exogenous and endogenous L1 elements are capable of homologous recombination, this seldom leads to crossing-overs. This observation could have implications for the stability of mammalian genomes.

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