scholarly journals The Mitochondrial DNA (mtDNA)-Associated Protein SWIB5 Influences mtDNA Architecture and Homologous Recombination

2017 ◽  
pp. tpc.00899.2016 ◽  
Author(s):  
Jonas Blomme ◽  
Olivier Van Aken ◽  
Jelle Van Leene ◽  
Teddy Jégu ◽  
Riet Maria De Rycke ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
Homologous Recombination

A mitochondrial retroplasmid integrates into mitochondrial DNA by a novel mechanism involving the synthesis of a hybrid cDNA and homologous recombination

1994 ◽  
Vol 14 (10) ◽  
pp. 6419-6432
Author(s):  
C C Chiang ◽  
J C Kennell ◽  
L A Wanner ◽  
A M Lambowitz
Keyword(s):  
Mitochondrial Dna ◽  
Homologous Recombination ◽  
Rrna Gene ◽  
Template Switching ◽  
Transcript Analysis ◽  
Wild Type ◽  
Mitochondrial Trna ◽  
Integration Mechanism ◽  
Circular Dnas ◽  
Simple Integration

The Mauriceville and Varkud mitochondrial plasmids of Neurospora spp. are closely related, small circular DNAs that propagate via an RNA intermediate and reverse transcription. Although the plasmids ordinarily replicate autonomously, they can also integrate into mitochondrial DNA (mtDNA), yielding defective mtDNAs that in some cases cause senescence. To investigate the integration mechanism, we analyzed four cases in which the Varkud plasmid integrated into the mitochondrial small rRNA gene, three in wild-type subcultures and one in a senescent mutant. Our analysis suggests that the integrations occurred by the plasmid reverse transcriptase template switching between the plasmid transcript and internal sequences in the mitochondrial small rRNA to yield hybrid cDNAs that circularized and recombined homologously with the mtDNA. The integrated plasmid sequences are transcribed, presumably from the mitochondrial small rRNA promoters, resulting in hybrid RNAs containing the 5' segment of the mitochondrial small rRNA linked head-to-tail to the full-length plasmid transcript. Analysis of additional senescent mutants revealed three cases in which the plasmid used the same mechanism to integrate at other locations in the mtDNA. In these cases, circular variant plasmids that had incorporated a mitochondrial tRNA or tRNA-like sequence by template switching integrated by homologous recombination at the site of the corresponding tRNA or tRNA-like sequence in mtDNA. This simple integration mechanism involving template switching to generate a hybrid cDNA that integrates homologously could have been used by primitive retroelements prior to the acquisition of a specialized integration machinery.

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.

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