Rearrangements of mitochondrial DNA and the mitochondrial fusion-promoting plasmid (mF) are associated with defective mitochondrial fusion in Physarum polycephalum

1996 ◽  
Vol 29 (3) ◽  
pp. 257-264 ◽  
Author(s):  
H. Takano ◽  
Tsuneyoshi Kuroiwa ◽  
Kimie Mori ◽  
Shigeyuki Kawano
Keyword(s):  
Mitochondrial Dna ◽  
Physarum Polycephalum ◽  
Mitochondrial Fusion

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.

Polymorphism, Heteroplasmy, Mitochondrial Fusion and Diabetes

2003 ◽  
Vol 23 (5-6) ◽  
pp. 313-337 ◽  
Author(s):  
Aya Sato ◽  
Hitoshi Endo ◽  
Kazuo Umetsu ◽  
Hideyuki Sone ◽  
Yoshiko Yanagisawa ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Mitochondrial Dna ◽  
Membrane Fusion ◽  
Coiled Coil ◽  
Reactive Oxygen ◽  
Mitochondrial Fusion ◽  
Vicious Circle ◽  
Oxygen Species ◽  
The Brain

Mitochondrial DNA (mtDNA) is highly susceptible to mutations that result in polymorphisms and diseases including diabetes. We analyzed heteroplasmy, polymorphisms related to diabetes, and complementation by fusogenic proteins. Cytoplast fusion and microinjection allow, defects in mutated mtDNA inside a heteroplasmic cell to be complemented by fusing two mitochondria via human fusogenic proteins. We characterized three hfzos as well as two OPA1s that prevent apoptosis. Two coiled coil domains and GTPase domains in these fusogenic proteins regulate membrane fusion. The hfzo genes were expressed mainly in the brain and in muscle that are postmitotic, but not in the pancreas. Under the in.uence of polymorphisms of mtDNA and nDNA, the vicious circle of reactive oxygen species and mutations in cell can be alleviated by mitochondrial fusion.

scholarly journals Polymorphism and Uniparental Inheritance of Mitochondrial DNA in Physarum polycephalum

Microbiology ◽  
1987 ◽  
Vol 133 (11) ◽  
pp. 3175-3182 ◽  
Author(s):  
S. Kawano ◽  
R. W. Anderson ◽  
T. Nanba ◽  
T. Kuroiwa
Keyword(s):  
Mitochondrial Dna ◽  
Physarum Polycephalum ◽  
Uniparental Inheritance
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