3tmm
From Proteopedia
TFAM imposes a U-turn on mitochondrial DNA
Structural highlights
Function[TFAM_HUMAN] Binds to the mitochondrial light strand promoter and functions in mitochondrial transcription regulation. Required for accurate and efficient promoter recognition by the mitochondrial RNA polymerase. Promotes transcription initiation from the HSP1 and the light strand promoter by binding immediately upstream of transcriptional start sites. Is able to unwind DNA. Bends the mitochondrial light strand promoter DNA into a U-turn shape via its HMG boxes. Required for maintenance of normal levels of mitochondrial DNA. May play a role in organizing and compacting mitochondrial DNA.[1] [2] [3] [4] [5] Publication Abstract from PubMedTfam (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 alpha-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. The mitochondrial transcription and packaging factor Tfam imposes a U-turn on mitochondrial DNA.,Ngo HB, Kaiser JT, Chan DC Nat Struct Mol Biol. 2011 Oct 30;18(11):1290-6. doi: 10.1038/nsmb.2159. PMID:22037171[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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Categories: Human | Chan, D C | Kaiser, J T | Ngo, H B | Dna | High mobility group | Hmg | Lsp1 | Mitochondria | Transcription | Transcription-dna complex
