6ero | pdb_00006ero
Structure of human TFB2M
Structural highlights
Function[TFB2M_HUMAN] S-adenosyl-L-methionine-dependent methyltransferase which specifically dimethylates mitochondrial 12S rRNA at the conserved stem loop. Also required for basal transcription of mitochondrial DNA, probably via its interaction with POLRMT and TFAM. Stimulates transcription independently of the methyltransferase activity. Compared to TFB1M, it activates transcription of mitochondrial DNA more efficiently, while it has less methyltransferase activity.[1] [2] [3] [4] Publication Abstract from PubMedTranscription in human mitochondria is driven by a single-subunit, factor-dependent RNA polymerase (mtRNAP). Despite its critical role in both expression and replication of the mitochondrial genome, transcription initiation by mtRNAP remains poorly understood. Here, we report crystal structures of human mitochondrial transcription initiation complexes assembled on both light and heavy strand promoters. The structures reveal how transcription factors TFAM and TFB2M assist mtRNAP to achieve promoter-dependent initiation. TFAM tethers the N-terminal region of mtRNAP to recruit the polymerase to the promoter whereas TFB2M induces structural changes in mtRNAP to enable promoter opening and trapping of the DNA non-template strand. Structural comparisons demonstrate that the initiation mechanism in mitochondria is distinct from that in the well-studied nuclear, bacterial, or bacteriophage transcription systems but that similarities are found on the topological and conceptual level. These results provide a framework for studying the regulation of gene expression and DNA replication in mitochondria. Structural Basis of Mitochondrial Transcription Initiation.,Hillen HS, Morozov YI, Sarfallah A, Temiakov D, Cramer P Cell. 2017 Nov 16;171(5):1072-1081.e10. doi: 10.1016/j.cell.2017.10.036. PMID:29149603[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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