Mechanism of initiation of yeast mitochondrial DNA replication: Role of RNA polymerase

1997 ◽  
Vol 22 (2) ◽  
pp. 149-159 ◽  
Author(s):  
Suzanne D’souza ◽  
K. Pasupathy
Keyword(s):  
Mitochondrial Dna ◽  
Dna Replication ◽  
Rna Polymerase ◽  
Mitochondrial Dna Replication ◽  
Yeast Mitochondrial Dna

scholarly journals Primer retention owing to the absence of RNase H1 is catastrophic for mitochondrial DNA replication

2015 ◽  
Vol 112 (30) ◽  
pp. 9334-9339 ◽  
Author(s):  
J. Bradley Holmes ◽  
Gokhan Akman ◽  
Stuart R. Wood ◽  
Kiran Sakhuja ◽  
Susana M. Cerritelli ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
Dna Replication ◽  
Strand Break ◽  
Initiation Site ◽  
Major Noncoding Region ◽  
Mitochondrial Dna Replication ◽  
Strand Initiation ◽  
Mitochondrial Dna Polymerase ◽  
Dna Maintenance

Encoding ribonuclease H1 (RNase H1) degrades RNA hybridized to DNA, and its function is essential for mitochondrial DNA maintenance in the developing mouse. Here we define the role of RNase H1 in mitochondrial DNA replication. Analysis of replicating mitochondrial DNA in embryonic fibroblasts lacking RNase H1 reveals retention of three primers in the major noncoding region (NCR) and one at the prominent lagging-strand initiation site termed Ori-L. Primer retention does not lead immediately to depletion, as the persistent RNA is fully incorporated in mitochondrial DNA. However, the retained primers present an obstacle to the mitochondrial DNA polymerase γ in subsequent rounds of replication and lead to the catastrophic generation of a double-strand break at the origin when the resulting gapped molecules are copied. Hence, the essential role of RNase H1 in mitochondrial DNA replication is the removal of primers at the origin of replication.

scholarly journals Saccharomyces cerevisiae contains an RNase MRP that cleaves at a conserved mitochondrial RNA sequence implicated in replication priming.

1992 ◽  
Vol 12 (6) ◽  
pp. 2561-2569 ◽  
Author(s):  
L L Stohl ◽  
D A Clayton
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mitochondrial Dna ◽  
Dna Replication ◽  
Rna Processing ◽  
Mitochondrial Rna ◽  
Rna Sequence ◽  
Rnase Mrp ◽  
Processing Activity ◽  
Yeast Mitochondrial Dna ◽  
Human And Mouse

Yeast mitochondrial DNA contains multiple promoters that sponsor different levels of transcription. Several promoters are individually located immediately adjacent to presumed origins of replication and have been suggested to play a role in priming of DNA replication. Although yeast mitochondrial DNA replication origins have not been extensively characterized at the primary sequence level, a common feature of these putative origins is the occurrence of a short guanosine-rich region in the priming strand downstream of the transcriptional start site. This situation is reminiscent of vertebrate mitochondrial DNA origins and raises the possibility of common features of origin function. In the case of human and mouse cells, there exists an RNA processing activity with the capacity to cleave at a guanosine-rich mitochondrial RNA sequence at an origin; we therefore sought the existence of a yeast endoribonuclease that had such a specificity. Whole cell and mitochondrial extracts of Saccharomyces cerevisiae contain an RNase that cleaves yeast mitochondrial RNA in a site-specific manner similar to that of the human and mouse RNA processing activity RNase MRP. The exact location of cleavage within yeast mitochondrial RNA corresponds to a mapped site of transition from RNA to DNA synthesis. The yeast activity also cleaved mammalian mitochondrial RNA in a fashion similar to that of the mammalian RNase MRPs. The yeast endonuclease is a ribonucleoprotein, as judged by its sensitivity to nucleases and proteinase, and it was present in yeast strains lacking mitochondrial DNA, which demonstrated that all components required for in vitro cleavage are encoded by nuclear genes. We conclude that this RNase is the yeast RNase MRP.

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