3TMM

TFAM imposes a U-turn on mitochondrial DNA

Summary for 3TMM

• Entry DOI: 10.2210/pdb3tmm/pdb
• Descriptor: Transcription factor A, mitochondrial, DNA (28-MER), ... (4 entities in total)
• Functional Keywords: hmg, high mobility group, transcription, lsp1, dna, mitochondria, transcription-dna complex, transcription/dna
• Biological source: Homo sapiens (human); More
• Cellular location: Mitochondrion: Q00059
• Total number of polymer chains: 3
• Total formula weight: 45634.33

Authors

Ngo, H.B.,Kaiser, J.T.,Chan, D.C. (deposition date: 2011-08-31, release date: 2011-11-09, Last modification date: 2024-10-16)

Primary citation

Ngo, H.B.,Kaiser, J.T.,Chan, D.C.
The mitochondrial transcription and packaging factor Tfam imposes a U-turn on mitochondrial DNA.
Nat.Struct.Mol.Biol., 18:1290-1296, 2011

PubMed Abstract: Tfam (transcription factor A, mitochondrial), a DNA-binding protein with tandem high-mobility group (HMG)-box domains, has a central role in the expression, maintenance and organization of the mitochondrial genome. It activates transcription from mitochondrial promoters and organizes the mitochondrial genome into nucleoids. Using X-ray crystallography, we show that human Tfam forces promoter DNA to undergo a U-turn, reversing the direction of the DNA helix. Each HMG-box domain wedges into the DNA minor groove to generate two kinks on one face of the DNA. On the opposite face, a positively charged α-helix serves as a platform to facilitate DNA bending. The structural principles underlying DNA bending converge with those of the unrelated HU family proteins, which have analogous architectural roles in organizing bacterial nucleoids. The functional importance of this extreme DNA bending is promoter specific and seems to be related to the orientation of Tfam on the promoters.

PubMed: 22037171
DOI: 10.1038/nsmb.2159

Experimental method

X-RAY DIFFRACTION (2.5001 Å)