9GZM

Cryo-EM structure of the human mitochondrial RNA polymerase transcription initiation complex (POLRMT/TFAM/TFB2M/DNA/RNA) with a 2-mer RNA (pppGpA) and GTP poised for catalysis (pre-IC3)

9GZM の概要

• エントリーDOI: 10.2210/pdb9gzm/pdb
• 関連するPDBエントリー: 9GZN 9GZO 9R95 9R96
• EMDBエントリー: 51727 51728 51729 53853 53854
• 分子名称: DNA-directed RNA polymerase, mitochondrial, Non-template strand DNA (56-MER), Template strand DNA (56-MER), ... (8 entities in total)
• 機能のキーワード: polrmt, tfb2m, tfam, transcription initiation, polymerase, h-mtrnap, mtrnap, rna polymerase, mitochondrial dna, mitochondria, transcription, slippage
• 由来する生物種: Homo sapiens (human); 詳細
• タンパク質・核酸の鎖数: 6
• 化学式量合計: 237017.38

構造登録者

Goovaerts, Q.,Shen, J.,Ajjugal, Y.,De Wijngaert, B.,Patel, S.S.,Das, K. (登録日: 2024-10-04, 公開日: 2025-07-30, 最終更新日: 2025-09-03)

主引用文献

Shen, J.,Goovaerts, Q.,Ajjugal, Y.,De Wijngaert, B.,Das, K.,Patel, S.S.
Human mitochondrial RNA polymerase structures reveal transcription start site and slippage mechanism.
Mol.Cell, 85:3137-3150.e7, 2025

PubMed Abstract: Transcription of the human mitochondrial DNA is initiated by POLRMT and initiation factors mitochondrial transcription factor A (TFAM) and mitochondrial transcription factor B2 (TFB2M). We present cryo-electron microscopy (cryo-EM) structures of three transcription initiation intermediates (pre-catalytic IC3 [pre-IC3], slipped-IC3, and slipped pre-IC4) catalyzing RNA synthesis by normal and slippage pathways with fully resolved transcription bubbles and RNA transcripts starting from the +1 or -1 position. The structural and biochemical studies reveal mechanisms of promoter melting, start site selection, and slippage synthesis. Promoter melting begins at -4 with base-specific interactions of template -4 and -3 guanines with POLRMT and non-template -1 adenine with TFB2M. The NT-stabilizing loop (KLDPRSGGVIKPP) and Y209 of TFB2M and W1026 of POLRMT interact with the non-template strand to guide initiation from the +1 start site. The -1 position is not an alternative start site but supports slippage initiation by base-pairing with a slipped or rebound 2-nt RNA. Cryo-EM resolved additional apo and dimeric complexes whose populations may regulate transcription initiation.

PubMed: 40712586
DOI: 10.1016/j.molcel.2025.07.002

実験手法

ELECTRON MICROSCOPY (3.4 Å)