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Revealing how DNA is compacted in the mitochondria
Mitochondria are the energy factories of our cells, and carry their own genome. Although generally extensively studied, very little is known about the compaction of the DNA inside mitochondria. The human mitochondrial transcription factor A (TFAM), an abundant protein inside mitochondria, has been suggested to play a key role in organizing mitochondrial DNA (mtDNA) besides acting as transcription initiator. Here, we use a combination of single molecule manipulation and fluorescence microscopy techniques to address the TFAM-DNA kinetics and elucidate the role of TFAM in mtDNA organisation. We show that TFAM binds unspecific yet cooperatively while softening the stiffness of DNA, resulting in an effective DNA compaction. Based on these observations, we propose a molecular mechanism in which the binding of TFAM induces local melting of the DNA, a mechanism it likely employs as well when acting as specific transcription regulator.
Séminaire NBP
Contact : ulrich.bockelmann@espci.fr