Sequence analysis of a Papaver somniferum L. mitochondrial DNA fragment promoting autonomous plasmid replication in Saccharomyces cerevisiae and Kluyveromyces lactis

1993 ◽  
Vol 24 (4) ◽  
pp. 366-367 ◽  
Author(s):  
Jarmila Farkašovská
Genetics ◽  
2000 ◽  
Vol 154 (1) ◽  
pp. 147-154 ◽  
Author(s):  
Douglas J Kominsky ◽  
Peter E Thorsness

Abstract Organisms that can grow without mitochondrial DNA are referred to as “petite-positive” and those that are inviable in the absence of mitochondrial DNA are termed “petite-negative.” The petite-positive yeast Saccharomyces cerevisiae can be converted to a petite-negative yeast by inactivation of Yme1p, an ATP- and metal-dependent protease associated with the inner mitochondrial membrane. Suppression of this yme1 phenotype can occur by virtue of dominant mutations in the α- and γ-subunits of mitochondrial ATP synthase. These mutations are similar or identical to those occurring in the same subunits of the same enzyme that converts the petite-negative yeast Kluyveromyces lactis to petite-positive. Expression of YME1 in the petite-negative yeast Schizosaccharomyces pombe converts this yeast to petite-positive. No sequence closely related to YME1 was found by DNA-blot hybridization to S. pombe or K. lactis genomic DNA, and no antigenically related proteins were found in mitochondrial extracts of S. pombe probed with antisera directed against Yme1p. Mutations that block the formation of the F1 component of mitochondrial ATP synthase are also petite-negative. Thus, the F1 complex has an essential activity in cells lacking mitochondrial DNA and Yme1p can mediate that activity, even in heterologous systems.


1993 ◽  
Vol 13 (5) ◽  
pp. 2697-2705
Author(s):  
R H Schiestl ◽  
M Dominska ◽  
T D Petes

When the yeast Saccharomyces cerevisiae was transformed with DNA that shares no homology to the genome, three classes of transformants were obtained. In the most common class, the DNA was inserted as the result of a reaction that appears to require base pairing between the target sequence and the terminal few base pairs of the transforming DNA fragment. In the second class, no such homology was detected, and the transforming DNA was integrated next to a CTT or GTT in the target; it is likely that these integration events were mediated by topoisomerase I. The final class involved the in vivo ligation of transforming DNA with nucleus-localized linear fragments of mitochondrial DNA.


1993 ◽  
Vol 13 (5) ◽  
pp. 2697-2705 ◽  
Author(s):  
R H Schiestl ◽  
M Dominska ◽  
T D Petes

When the yeast Saccharomyces cerevisiae was transformed with DNA that shares no homology to the genome, three classes of transformants were obtained. In the most common class, the DNA was inserted as the result of a reaction that appears to require base pairing between the target sequence and the terminal few base pairs of the transforming DNA fragment. In the second class, no such homology was detected, and the transforming DNA was integrated next to a CTT or GTT in the target; it is likely that these integration events were mediated by topoisomerase I. The final class involved the in vivo ligation of transforming DNA with nucleus-localized linear fragments of mitochondrial DNA.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Silvia Bágeľová Poláková ◽  
Žaneta Lichtner ◽  
Tomáš Szemes ◽  
Martina Smolejová ◽  
Pavol Sulo

AbstractmtDNA recombination events in yeasts are known, but altered mitochondrial genomes were not completed. Therefore, we analyzed recombined mtDNAs in six Saccharomyces cerevisiae × Saccharomyces paradoxus hybrids in detail. Assembled molecules contain mostly segments with variable length introgressed to other mtDNA. All recombination sites are in the vicinity of the mobile elements, introns in cox1, cob genes and free standing ORF1, ORF4. The transplaced regions involve co-converted proximal exon regions. Thus, these selfish elements are beneficial to the host if the mother molecule is challenged with another molecule for transmission to the progeny. They trigger mtDNA recombination ensuring the transfer of adjacent regions, into the progeny of recombinant molecules. The recombination of the large segments may result in mitotically stable duplication of several genes.


Genetics ◽  
2001 ◽  
Vol 157 (4) ◽  
pp. 1569-1579 ◽  
Author(s):  
Michael L Rolfsmeier ◽  
Michael J Dixon ◽  
Luis Pessoa-Brandão ◽  
Richard Pelletier ◽  
Juan José Miret ◽  
...  

Abstract Trinucleotide repeat (TNR) instability in humans is governed by unique cis-elements. One element is a threshold, or minimal repeat length, conferring frequent mutations. Since thresholds have not been directly demonstrated in model systems, their molecular nature remains uncertain. Another element is sequence specificity. Unstable TNR sequences are almost always CNG, whose hairpin-forming ability is thought to promote instability by inhibiting DNA repair. To understand these cis-elements further, TNR expansions and contractions were monitored by yeast genetic assays. A threshold of ∼15–17 repeats was observed for CTG expansions and contractions, indicating that thresholds function in organisms besides humans. Mutants lacking the flap endonuclease Rad27p showed little change in the expansion threshold, suggesting that this element is not altered by the presence or absence of flap processing. CNG or GNC sequences yielded frequent mutations, whereas A-T rich sequences were substantially more stable. This sequence analysis further supports a hairpin-mediated mechanism of TNR instability. Expansions and contractions occurred at comparable rates for CTG tract lengths between 15 and 25 repeats, indicating that expansions can comprise a significant fraction of mutations in yeast. These results indicate that several unique cis-elements of human TNR instability are functional in yeast.


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