Regulation of mitochondrial D-loops by transcription factor A and single-stranded DNA-binding protein

Chihiro Takamatsu, Shuyo Umeda, Takashi Ohsato, Tersuji Ohno, Yoshito Abe, Atsushi Fukuoh, Hideo Shinagawa, Naotaka Hamasaki, Dongchon Kang

Research output: Contribution to journalArticlepeer-review

159 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)451-456
Number of pages6
JournalEMBO Reports
Volume3
Issue number5
DOIs
Publication statusPublished - Jan 1 2002

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Genetics

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