Mammalian transcription factor A is a core component of the mitochondrial transcription machinery
Journal article, 2012

Transcription factor A (TFAM) functions as a DNA packaging factor in mammalian mitochondria. TFAM also binds sequence-specifically to sites immediately upstream of mitochondrial promoters, but there are conflicting data regarding its role as a core component of the mitochondrial transcription machinery. We here demonstrate that TFAM is required for transcription in mitochondrial extracts as well as in a reconstituted in vitro transcription system. The absolute requirement of TFAM can be relaxed by conditions that allow DNA breathing, i.e., low salt concentrations or negatively supercoiled DNA templates. The situation is thus very similar to that described in nuclear RNA polymerase II-dependent transcription, in which the free energy of supercoiling can circumvent the need for a subset of basal transcription factors at specific promoters. In agreement with these observations, we demonstrate that TFAM has the capacity to induce negative supercoils in DNA, and, using the recently developed nucleobase analog FRET-pair tC(O)-tC(nitro), we find that TFAM distorts significantly the DNA structure. Our findings differ from recent observations reporting that TFAM is not a core component of the mitochondrial transcription machinery. Instead, our findings support a model in which TFAM is absolutely required to recruit the transcription machinery during initiation of transcription.

Author

Yonghong Shi

University of Gothenburg

Anke Dierckx

Chalmers, Chemical and Biological Engineering, Physical Chemistry

Paulina Wanrooij

University of Gothenburg

Sjoerd Wanrooij

University of Gothenburg

N. G. Larsson

Max Planck Institute

Karolinska Institutet

Marcus Wilhelmsson

Chalmers, Chemical and Biological Engineering, Physical Chemistry

Maria Falkenberg

University of Gothenburg

Claes M Gustafsson

University of Gothenburg

Proceedings of the National Academy of Sciences of the United States of America

0027-8424 (ISSN) 1091-6490 (eISSN)

Vol. 109 41 16510-16515

Areas of Advance

Nanoscience and Nanotechnology (2010-2017)

Life Science Engineering (2010-2018)

Subject Categories

Physical Chemistry

Biochemistry and Molecular Biology

DOI

10.1073/pnas.1119738109

More information

Latest update

2/21/2018