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Regulation of mitochondrial D‐loops by transcription factor A and single‐stranded DNA‐binding protein
Author(s) -
Takamatsu Chihiro,
Umeda Shuyo,
Ohsato Takashi,
Ohno Tetsuji,
Abe Yoshito,
Fukuoh Atsushi,
Shinagawa Hideo,
Hamasaki Naotaka,
Kang Dongchon
Publication year - 2002
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.1093/embo-reports/kvf099
Subject(s) - tfam , mitochondrial dna , biology , helicase , dna , microbiology and biotechnology , dna replication , transcription (linguistics) , dna binding protein , transcription factor , genetics , gene , rna , linguistics , philosophy
During replication, mitochondrial DNA (mtDNA) takes on a triple‐stranded structure called a D‐loop. Although their physiological roles are not understood, D‐loops are implicated in replication and transcription of mtDNA. Little is known about the turnover of D‐loops. We investigated the effects of mitochondrial transcription factor A (TFAM) and single‐stranded DNA‐binding protein (mtSSB) on D‐loops. In human HeLa cells, TFAM and mtSSB are, respectively, 1700‐ and 3000‐fold more abundant than mtDNA. This level of TFAM is two orders of magnitude higher than reported previously and is sufficient to wrap human mtDNA entirely. TFAM resolves D‐loops in vitro if added in similar stoichiometries. mtSSB inhibits the resolution of mtDNA by TFAM but enhances resolution by RecG, a junction‐specific helicase from Escherichia coli . Hence, mtSSB functions in both stabilization and resolution. We propose that TFAM and mtSSB are cooperatively involved in stabilizing D‐loops and in the maintenance of mtDNA.