title: A novel intermediate in transcription initiation by human mitochondrial RNA polymerase.
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.
authors.affiliation: 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.
authors.forename: Yaroslav I
authors.initials: YI
authors.lastname: Morozov
authors.forename: Karen
authors.initials: K
authors.lastname: Agaronyan
authors.forename: Alan C M
authors.initials: AC
authors.lastname: Cheung
authors.forename: Michael
authors.initials: M
authors.lastname: Anikin
authors.forename: Patrick
authors.initials: P
authors.lastname: Cramer
authors.forename: Dmitry
authors.initials: D
authors.lastname: Temiakov
mesh_terms: D004268:DNA-Binding Proteins / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D024101:Mitochondrial Proteins / Q000378:metabolism; D011401:Promoter Regions, Genetic; D054730:Protein Interaction Domains and Motifs; D014157:Transcription Factors / Q000378:metabolism; D061785:Transcription Initiation, Genetic
chemical_list: D004268:DNA-Binding Proteins; D024101:Mitochondrial Proteins; C499631:TFAM protein, human; D014157:Transcription Factors; D012321:DNA-Directed RNA Polymerases; C519567:POLRMT protein, human