title: The AAA+ protein ATAD3 has displacement loop binding properties and is involved in mitochondrial nucleoid organization.
abstract: Many copies of mammalian mitochondrial DNA contain a short triple-stranded region, or displacement loop (D-loop), in the major noncoding region. In the 35 years since their discovery, no function has been assigned to mitochondrial D-loops. We purified mitochondrial nucleoprotein complexes from rat liver and identified a previously uncharacterized protein, ATAD3p. Localization studies suggested that human ATAD3 is a component of many, but not all, mitochondrial nucleoids. Gene silencing of ATAD3 by RNA interference altered the structure of mitochondrial nucleoids and led to the dissociation of mitochondrial DNA fragments held together by protein, specifically, ones containing the D-loop region. In vitro, a recombinant fragment of ATAD3p bound to supercoiled DNA molecules that contained a synthetic D-loop, with a marked preference over partially relaxed molecules with a D-loop or supercoiled DNA circles. These results suggest that mitochondrial D-loops serve to recruit ATAD3p for the purpose of forming or segregating mitochondrial nucleoids.
authors.affiliation: Medical Research Council Dunn Human Nutrition Unit, Wellcome Trust/Medical Research Council Building, Cambridge CB2 OXY, England, UK.
authors.forename: Jiuya
authors.initials: J
authors.lastname: He
authors.forename: Chih-Chieh
authors.initials: CC
authors.lastname: Mao
authors.forename: Aurelio
authors.initials: A
authors.lastname: Reyes
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sembongi
authors.forename: Miriam
authors.initials: M
authors.lastname: Di Re
authors.forename: Caroline
authors.initials: C
authors.lastname: Granycome
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Clippingdale
authors.forename: Ian M
authors.initials: IM
authors.lastname: Fearnley
authors.forename: Michael
authors.initials: M
authors.lastname: Harbour
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Robinson
authors.forename: Stefanie
authors.initials: S
authors.lastname: Reichelt
authors.forename: Johannes N
authors.initials: JN
authors.lastname: Spelbrink
authors.forename: John E
authors.initials: JE
authors.lastname: Walker
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Holt
mesh_terms: D000074183:ATPases Associated with Diverse Cellular Activities; D000251:Adenosine Triphosphatases; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D045744:Cell Line, Tumor; D004272:DNA, Mitochondrial / Q000235:genetics / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000378:metabolism; D004278:DNA, Superhelical / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D024202:Electrophoretic Mobility Shift Assay; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008930:Mitochondria, Liver / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D009690:Nucleic Acid Conformation; D009698:Nucleoproteins / Q000235:genetics / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D034741:RNA, Small Interfering / Q000235:genetics; D051381:Rats; D013367:Submitochondrial Particles / Q000378:metabolism*
chemical_list: C549686:ATAD3A protein, human; C519737:ATAD3B protein, human; D004272:DNA, Mitochondrial; D004277:DNA, Single-Stranded; D004278:DNA, Superhelical; D004268:DNA-Binding Proteins; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D009698:Nucleoproteins; D010446:Peptide Fragments; D034741:RNA, Small Interfering; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D000074183:ATPases Associated with Diverse Cellular Activities