2007 Fiscal Year Final Research Report Summary
A Novel Regulatory Mechanism for Initiation of Mitochondrial DNA Replication
| Project/Area Number |
18570168
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Molecular biology
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| Research Institution | The Institute of Physical and Chemical Research |
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Principal Investigator |
FENG Ling The Institute of Physical and Chemical Research, Chemical Genetics Laboratory, Senior Research Scientist (70281665)
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| Project Period (FY) |
2006 – 2007
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| Keywords | DNA double-strand break / Saccharomyces cerevisiae / Homologous DNA recombination / Rolling circle DNA replication / Concatemer / Homoplasmv / Heteroplasmv / DNA repair |
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| Research Abstract |
Mitochondrial DNA (mtDNA) genomic copy number largely varies under different physiological conditions, but the mechanism underlying regulation of mtDNA copy number still remains unknown. Our previous results revealed that in the yeast Saccharomyces wrevisiae, mtDNA replication mainly depends on a recombination-mediated rolling circle type replication, and the initiation is dependent on a double-stranded break in a replication origin (on5).
This year we analyzed the function of the novel protein, Imrl, the ove-expression of which suppresses replication advantage of hypersuppressive [rho^-] mtDNA over normal[rho^+] mtDNA, and the level of the double-stranded break at the ori5site. To identify the localization of Imr1, Western blot analysis was performed by using antibody against Imrl to detect the signals of Imr1 in mitochondria isolated from Imrl-overproducing cells and empty vector harboring cells. We found that the signals of Imrl only increased in mitochondria derived from the cells with overproduced Imrl, indicating Imrl is localized in mitochondria.
To examine the effect of over-expression of IMR1 gene on the replication of mtDNA, Southern blot analysis was performed to quantitatively measure the mtDNA copy number We found that the copy number of hypersuppressive[rho^-] mtDNA decreased to one-fifth of that in the cells without overproduced Imrl. We further found that the amounts of the major molecular species of hypersuppressive [rhol^-] mtDNA, including concatemers that are formed through rolling circle type replication and circular multimers that are formed by homologous recombination remarkably decreased in the Imrl-overproducing cells.
These results suggest that Imrl plays a role in the regulation of the recombination-mediated rolling circle type replication by directly suppressing the formation of the double stranded break in ori5 in yeast mitochondria.
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Research Products
(18 results)
