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Free keywords:
Adenosine Triphosphate/genetics/metabolism
Crystallography, X-Ray
DNA, Mitochondrial/*genetics
DNA-Binding Proteins/*chemistry
Gene Expression Regulation
Mitochondria/*genetics
Mitochondrial Proteins/*chemistry
Oxidative Phosphorylation
Protein Conformation
Transcription Factors/*chemistry
*Transcription Initiation, Genetic
Tfam
mitochondrial nucleoid
mtDNA
Abstract:
Mitochondria contain mtDNA derived from the ancestral endosymbiont genome. Important subunits of the oxidative phosphorylation system, which supplies cells with the energy currency ATP, are encoded by mtDNA. A naked mtDNA molecule is longer than a typical mitochondrion and is therefore compacted in vivo to form a nucleoprotein complex, denoted the mitochondrial nucleoid. Mitochondrial transcription factor A (TFAM) is the main factor packaging mtDNA into nucleoids and is also essential for mtDNA transcription initiation. The crystal structure of TFAM shows that it bends mtDNA in a sharp U-turn, which likely provides the structural basis for its dual functions. Super-resolution imaging studies have revealed that the nucleoid has an average diameter of approximately 100nm and frequently contains a single copy of mtDNA. In this review the structure of the mitochondrial nucleoid and its possible regulatory roles in mtDNA expression will be discussed.
