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Nucleic Acids Res. 2014 Apr;42(6):3884-93. doi: 10.1093/nar/gkt1356. Epub 2014 Jan 6.

A novel intermediate in transcription initiation by human mitochondrial RNA polymerase.

Author information

1
Department of Cell Biology, School of Osteopathic Medicine, Rowan University, Medical Center Dr, Stratford, NJ 08084, USA and Gene Center and Department of Biochemistry, Center for Integrated Protein Science Munich (CIPSM), Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 Munich, Germany.

Abstract

The mitochondrial genome is transcribed by a single-subunit T7 phage-like RNA polymerase (mtRNAP), structurally unrelated to cellular RNAPs. In higher eukaryotes, mtRNAP requires two transcription factors for efficient initiation-TFAM, a major nucleoid protein, and TFB2M, a transient component of mtRNAP catalytic site. The mechanisms behind assembly of the mitochondrial transcription machinery and its regulation are poorly understood. We isolated and identified a previously unknown human mitochondrial transcription intermediate-a pre-initiation complex that includes mtRNAP, TFAM and promoter DNA. Using protein-protein cross-linking, we demonstrate that human TFAM binds to the N-terminal domain of mtRNAP, which results in bending of the promoter DNA around mtRNAP. The subsequent recruitment of TFB2M induces promoter melting and formation of an open initiation complex. Our data indicate that the pre-initiation complex is likely to be an important target for transcription regulation and provide basis for further structural, biochemical and biophysical studies of mitochondrial transcription.

PMID:
24393772
PMCID:
PMC3973326
DOI:
10.1093/nar/gkt1356
[Indexed for MEDLINE]
Free PMC Article

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