The mammalian mitochondrial transcription factor A (TFAM) is encoded in the nucleus and imported into mitochondria, where it functions as an activator of mtDNA transcription and packages mtDNA into DNA-protein aggregates called mitochondrial nucleoids. Two studies in this issue reveal that TFAM shapes mtDNA into a sharp U-turn, providing a molecular mechanism for its dual roles in the expression and maintenance of mtDNA.
- B Martin Hallberg
- Nils-Göran Larsson