scholarly journals RPO41-independent maintenance of [rho-] mitochondrial DNA in Saccharomyces cerevisiae.

1990 ◽  
Vol 10 (1) ◽  
pp. 10-15 ◽  
Author(s):  
W L Fangman ◽  
J W Henly ◽  
B J Brewer
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mitochondrial Dna ◽  
Rna Polymerase ◽  
Nuclear Gene ◽  
Replication Initiation ◽  
Yeast Cells ◽  
Mitochondrial Rna ◽  
Yeast Saccharomyces Cerevisiae ◽  
Mitochondrial Rna Polymerase ◽  
Mtdna Deletion

A subset of promoters in the mitochondrial DNA (mtDNA) of the yeast Saccharomyces cerevisiae has been proposed to participate in replication initiation, giving rise to a primer through site-specific cleavage of an RNA transcript. To test whether transcription is essential for mtDNA maintenance, we examined two simple mtDNA deletion ([rho-]) genomes in yeast cells. One genome (HS3324) contains a consensus promoter (ATATAAGTA) for the mitochondrial RNA polymerase encoded by the nuclear gene RPO41, and the other genome (4a) does not. As anticipated, in RPO41 cells transcripts from the HS3324 genome were more abundant than were transcripts from the 4a genome. When the RPO41 gene was disrupted, both [rho-] genomes were efficiently maintained. The level of transcripts from HS3324 mtDNA was decreased greater than 400-fold in cells carrying the RPO41 disrupted gene; however, the low-level transcripts from 4a mtDNA were undiminished. These results indicate that replication of [rho-] genomes can be initiated in the absence of wild-type levels of the RPO41-encoded RNA polymerase.

RPO41-independent maintenance of [rho-] mitochondrial DNA in Saccharomyces cerevisiae

1990 ◽  
Vol 10 (1) ◽  
pp. 10-15
Author(s):  
W L Fangman ◽  
J W Henly ◽  
B J Brewer
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mitochondrial Dna ◽  
Rna Polymerase ◽  
Nuclear Gene ◽  
Replication Initiation ◽  
Yeast Cells ◽  
Mitochondrial Rna ◽  
Yeast Saccharomyces Cerevisiae ◽  
Mitochondrial Rna Polymerase ◽  
Mtdna Deletion

A subset of promoters in the mitochondrial DNA (mtDNA) of the yeast Saccharomyces cerevisiae has been proposed to participate in replication initiation, giving rise to a primer through site-specific cleavage of an RNA transcript. To test whether transcription is essential for mtDNA maintenance, we examined two simple mtDNA deletion ([rho-]) genomes in yeast cells. One genome (HS3324) contains a consensus promoter (ATATAAGTA) for the mitochondrial RNA polymerase encoded by the nuclear gene RPO41, and the other genome (4a) does not. As anticipated, in RPO41 cells transcripts from the HS3324 genome were more abundant than were transcripts from the 4a genome. When the RPO41 gene was disrupted, both [rho-] genomes were efficiently maintained. The level of transcripts from HS3324 mtDNA was decreased greater than 400-fold in cells carrying the RPO41 disrupted gene; however, the low-level transcripts from 4a mtDNA were undiminished. These results indicate that replication of [rho-] genomes can be initiated in the absence of wild-type levels of the RPO41-encoded RNA polymerase.

scholarly journals A test of the transcription model for biased inheritance of yeast mitochondrial DNA.

1995 ◽  
Vol 15 (9) ◽  
pp. 4803-4809 ◽  
Author(s):  
H E Lorimer ◽  
B J Brewer ◽  
W L Fangman
Keyword(s):  
Mitochondrial Dna ◽  
Nuclear Gene ◽  
Replication Initiation ◽  
High Density ◽  
Mitochondrial Rna ◽  
Wild Type ◽  
Mitochondrial Rna Polymerase ◽  
Origin Region ◽  
Mtdna Replication ◽  
Yeast Mitochondrial Dna

Two strand-specific origins of replication appear to be required for mammalian mitochondrial DNA (mtDNA) replication. Structural equivalents of these origins are found in the rep sequences of Saccharomyces cerevisiae mtDNA. These striking similarities have contributed to a universal model for the initiation of mtDNA replication in which a primer is created by cleavage of an origin region transcript. Consistent with this model are the properties of deletion mutants of yeast mtDNA ([rho-]) with a high density of reps (HS [rho-]). These mutant mtDNAs are preferentially inherited by the progeny resulting from the mating of HS [rho-] cells with cells containing wild-type mtDNA ([rho+]). This bias is presumed to result from a replication advantage conferred on HS [rho-] mtDNA by the high density of rep sequences acting as origins. To test whether transcription is indeed required for the preferential inheritance of HS [rho-] mtDNA, we deleted the nuclear gene (RPO41) for the mitochondrial RNA polymerase, reducing transcripts by at least 1000-fold. Since [rho-] genomes, but not [rho+] genomes, are stable when RPO41 is deleted, we examined matings between HS [rho-] and neutral [rho-] cells. Neutral [rho-] mtDNAs lack rep sequences and are not preferentially inherited in [rho-] x [rho+] crosses. In HS [rho-] x neutral [rho-] matings, the HS [rho-] mtDNA was preferentially inherited whether both parents were wild type or both were deleted for RPO41. Thus, transcription from the rep promoter does not appear to be necessary for biased inheritance. Our results, and analysis of the literature, suggest that priming by transcription is not a universal mechanism for mtDNA replication initiation.

scholarly journals Distinct roles for two purified factors in transcription of Xenopus mitochondrial DNA.

1995 ◽  
Vol 15 (12) ◽  
pp. 7032-7042 ◽  
Author(s):  
I Antoshechkin ◽  
D F Bogenhagen
Keyword(s):  
Mitochondrial Dna ◽  
Rna Polymerase ◽  
Sequence Similarity ◽  
Protein A ◽  
Mitochondrial Rna ◽  
Basal Transcription ◽  
Hmg Box ◽  
Mitochondrial Rna Polymerase ◽  
Dnase I Footprinting

Transcription of Xenopus laevis mitochondrial DNA (xl-mtDNA) by the mitochondrial RNA polymerase requires a dissociable factor. This factor was purified to near homogeneity and identified as a 40-kDa protein. A second protein implicated in the transcription of mtDNA, the Xenopus homolog of the HMG box protein mtTFA, was also purified to homogeneity and partially sequenced. The sequence of a cDNA clone encoding xl-mtTFA revealed a high degree of sequence similarity to human and Saccharomyces cerevisiae mtTFA. xl-mtTFA was not required for basal transcription from a minimal mtDNA promoter, and this HMG box factor could not substitute for the basal factor, which is therefore designated xl-mtTFB. An antibody directed against the N terminus of xl-mtTFA did not cross-react with xl-mtTFB. xl-mtTFA is an abundant protein that appears to have at least two functions in mitochondria. First, it plays a major role in packaging mtDNA within the organelle. Second, DNase I footprinting experiments identified preferred binding sites for xl-mtTFA within the control region of mtDNA next to major mitochondrial promoters. We show that binding of xl-mtTFA to a site separating the two clusters of bidirectional promoters selectively stimulates specific transcription in vitro by the basal transcription machinery, comprising mitochondrial RNA polymerase and xl-mtTFB.

scholarly journals Non-DNA-Templated Addition of Nucleotides to the 3′ End of RNAs by the Mitochondrial RNA Polymerase of Physarum polycephalum

2008 ◽  
Vol 28 (18) ◽  
pp. 5795-5802 ◽  
Author(s):  
Mara L. Miller ◽  
Dennis L. Miller
Keyword(s):  
Mitochondrial Dna ◽  
Rna Polymerase ◽  
Rna Editing ◽  
Physarum Polycephalum ◽  
Mitochondrial Gene ◽  
In Vitro Transcription ◽  
Open Reading Frames ◽  
Mitochondrial Rna ◽  
Mitochondrial Rna Polymerase

ABSTRACT Mitochondrial gene expression is necessary for proper mitochondrial biogenesis. Genes on the mitochondrial DNA are transcribed by a dedicated mitochondrial RNA polymerase (mtRNAP) that is encoded in the nucleus and imported into mitochondria. In the myxomycete Physarum polycephalum, nucleotides that are not specified by the mitochondrial DNA templates are inserted into some RNAs, a process called RNA editing. This is an essential step in the expression of these RNAs, as the insertion of the nontemplated nucleotides creates open reading frames for the production of proteins from mRNAs or produces required secondary structure in rRNAs and tRNAs. The nontemplated nucleotide is added to the 3′ end of the RNA as the RNA is being synthesized during mitochondrial transcription. Because RNA editing is cotranscriptional, the mtRNAP is implicated in RNA editing as well as transcription. We have cloned the cDNA for the mtRNAP of Physarum and have expressed the mtRNAP in Escherichia coli. We have used in vitro transcription assays based on the Physarum mtRNAP to identify a novel activity associated with the mtRNAP in which non-DNA-templated nucleotides are added to the 3′ end of RNAs. Any of the four ribonucleoside triphosphates (rNTPs) can act as precursors for this process, and this novel activity is observed when only one rNTP is supplied, a condition under which transcription does not occur. The implications of this activity for the mechanism of RNA editing are discussed.

Yeast mitochondrial RNA polymerase primes mitochondrial DNA polymerase at origins of replication and promoter sequences

Mitochondrion ◽  
2015 ◽  
Vol 24 ◽  
pp. 22-31 ◽  
Author(s):  
Eugenia Sanchez-Sandoval ◽  
Corina Diaz-Quezada ◽  
Gilberto Velazquez ◽  
Luis F. Arroyo-Navarro ◽  
Norineli Almanza-Martinez ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
Rna Polymerase ◽  
Dna Polymerase ◽  
Mitochondrial Rna ◽  
Promoter Sequences ◽  
Mitochondrial Rna Polymerase ◽  
Origins Of Replication ◽  
Mitochondrial Dna Polymerase

scholarly journals A nuclear mutation reversing a biased transmission of yeast mitochondrial DNA.

Genetics ◽  
1991 ◽  
Vol 128 (2) ◽  
pp. 241-249 ◽  
Author(s):  
S G Zweifel ◽  
W L Fangman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mitochondrial Dna ◽  
Nuclear Gene ◽  
Diploid Strain ◽  
Yeast Saccharomyces Cerevisiae ◽  
Mtdna Replication ◽  
Clonal Lines ◽  
Yeast Mitochondrial Dna ◽  
P Cells ◽  
Allele Transmission

Abstract The highly biased transmission of p- mitochondrial DNA that occurs in hypersuppressive matings between p- and p+ cells of the yeast Saccharomyces cerevisiae is thought to be a consequence of the replication advantage of the p- mtDNA. A nuclear gene, MGT1, that is required for this displacement of p+ mtDNA from zygotic clones has been identified through mutation. When one haploid parent carries the mgt1 allele, transmission of p- mtDNA is substantially reduced. When both haploid parents carry the mgt1 allele, p- mtDNA is essentially eliminated from the zygotic progeny. Thus in the absence of the MGT1 gene there is a switch in the transmission bias; p+ mtDNA rather than the hypersuppressive p- mtDNA is inherited by most zygotic clones. In contrast to its semi-dominant behavior in haploid matings, mgt1 behaves as a recessive allele in diploid matings since the p+ genome in MGT1/mgt1 diploids is efficiently displaced when mated with a MGT1/mgt1 hypersuppressive p- diploid strain. We find that p+ genomes can be comaintained along with hypersuppressive p- mtDNA for extended periods in clonal lines derived from MGT1 x mgt1 matings. However, as expected from the recessive nature of the mgt1 mutation, these p+ genomes are eventually eliminated. Our work indicates that MGT1 plays a crucial role in the competition for inheritance between hypersuppressive p- mtDNAs and the p+ mitochondrial genome. The MGT1 gene product may be a component of a mtDNA replication system that acts preferentially at the rep sequences found in hypersuppressive mtDNAs.

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