4.8 Article

Cross-strand binding of TFAM to a single mtDNA molecule forms the mitochondrial nucleoid

Publisher

NATL ACAD SCIENCES
DOI: 10.1073/pnas.1512131112

Keywords

nucleoids; mitochondria; cryo-ET; STED; nanoscopy

Funding

  1. Deutsche Forschungsgemeinschaft (DFG) Center for Nanoscale Microscopy and Physiology of the Brain (CNMPB)
  2. DFG [SFB 829]
  3. European Research Council

Ask authors/readers for more resources

Mammalian mitochondrial DNA (mtDNA) is packaged by mitochondrial transcription factor A (TFAM) into mitochondrial nucleoids that are of key importance in controlling the transmission and expression of mtDNA. Nucleoid ultrastructure is poorly defined, and therefore we used a combination of biochemistry, super-resolution microscopy, and electron microscopy to show that mitochondrial nucleoids have an irregular ellipsoidal shape and typically contain a single copy of mtDNA. Rotary shadowing electron microscopy revealed that nucleoid formation in vitro is a multistep process initiated by TFAM aggregation and cross-strand binding. Superresolution microscopy of cultivated cells showed that increased mtDNA copy number increases nucleoid numbers without altering their sizes. Electron cryo-tomography visualized nucleoids at high resolution in isolated mammalian mitochondria and confirmed the sizes observed by superresolution microscopy of cell lines. We conclude that the fundamental organizational unit of the mitochondrial nucleoid is a single copy of mtDNA compacted by TFAM, and we suggest a packaging mechanism.

Authors

I am an author on this paper
Click your name to claim this paper and add it to your profile.

Reviews

Primary Rating

4.8
Not enough ratings

Secondary Ratings

Novelty
-
Significance
-
Scientific rigor
-
Rate this paper

Recommended

No Data Available
No Data Available