TAILIEUCHUNG - Báo cáo Y học: Mammalian mitochondrial endonuclease G Digestion of R-loops and localization in intermembrane space

Mammalian mitochondria contain strong nuclease activity. Endonuclease G (endoG), which predominantly resides in mitochondria, accounts for a large part of this nuclease activity. It has been proposed to act as an RNase H-like nuclease on RNAÆDNA hybrids (R-loops) in the D-loop region where the origins of mitochondrial replication are mapped, providing RNA primers for mtDNA replication. | Eur. J. Biochem. 269 5765-5770 2002 FEBS 2002 doi Mammalian mitochondrial endonuclease G Digestion of R-loops and localization in intermembrane space Takashi Ohsato1 Naotada Ishihara2. Tsuvoshi Muta1. Shuvo Umeda1. Shoao Ikeda3 Katsuvoshi Mihara2 Naotaka Hamasaki1 and Dongchon Kang1 1 Department of Clinical Chemistry and Laboratory Medicine Kyushu University Graduate School of Medical Sciences Fukuoka Japan 2Department of Molecular Biology Graduate School of Medical Sciences Kyushu University Fukuoka Japan 3Department of Biochemistry Faculty of Science Okayama University of Science Japan Mammalian mitochondria contain strong nuclease activity. Endonuclease G endoG which predominantly resides in mitochondria accounts for a large part of this nuclease activity. It has been proposed to act as an RNase H-like nuclease on RNA-DNA hybrids R-loops in the D-loop region where the origins of mitochondrial replication are mapped providing RNA primers for mtDNA replication. However in contrast with this proposed activity endoG has recently been shown to translocate to nuclei on apoptotic stimulation and act as a nuclease without sequence specificity. To clarify the role of endoG in mtDNA replication we examined its submitochondrial localization and its ability to cleave R-loops. At low concentration it preferentially produces double-stranded breaks in R-loops but does not act as an RNase H-like nuclease. In addition it exists in the mitochondrial intermembrane space but not in the matrix where mtDNA replication occurs. These results do not support the involvement of endoG in mtDNA replication. Based on the fact that guanine tracts which are preferential targets of endoG tend to form triplex structures and that endoG produces double-stranded breaks in R-loops we propose that three-stranded DNA may be the preferred substrate of endoG. Keywords endonuclease G mitochondria mitochondrial DNA R-loop triplex DNA. Mammalian mitochondria contain strong

• Báo cáo khoa học
• Report medicine
• traditional medicine
• scientific reports
• oxidation
• chemical reaction
• tumor cells
• medical knowledge
• medical research
• analysis of cytoplasmic
• Crystal structure
• bacteria
• hemoglobin
• medicine
• cell proliferation
• breast cancer
• gastric cancer
• hormone medicine
• biochemical studies
• environmental medicine