9EA2

T4 Bacteriophage Replicative Polymerase Captured in Polymerase Exchange State 2

9EA2 の概要

• エントリーDOI: 10.2210/pdb9ea2/pdb
• EMDBエントリー: 47824
• 分子名称: DNA-directed DNA polymerase, Sliding clamp, DNA (5'-AGC TAT GAC CAT GAT TAC GAA TTG ddC-3'), ... (4 entities in total)
• 機能のキーワード: replication, t4, holoenzyme, replication-dna complex, replication/dna
• 由来する生物種: Escherichia phage T4; 詳細
• タンパク質・核酸の鎖数: 7
• 化学式量合計: 301408.79

構造登録者

Li, H.,Feng, X. (登録日: 2024-11-10, 公開日: 2025-11-19, 最終更新日: 2026-01-14)

主引用文献

Feng, X.,Spiering, M.M.,Ruda de Luna Santos, A.,Benkovic, S.J.,Li, H.
Structural insights into the exchange mechanism of a replicative DNA polymerase.
Nucleic Acids Res., 53:-, 2025

PubMed Abstract: Replicative DNA polymerases are distinguished by their speed, processivity, and fidelity. While speed and fidelity arise from the polymerase's intrinsic catalytic and proofreading activities, processivity is typically attributed to the DNA sliding clamp that tethers the polymerase to DNA. However, additional mechanisms may also contribute. The T4 bacteriophage polymerase can exchange on-the-fly, a process likely contributing to its ∼10-fold higher synthesis rate compared with human polymerases. Here, we reconstituted the T4 holoenzyme and polymerase exchange complexes using purified gp43 polymerase, gp45 sliding clamp, and a primer-template DNA substrate. Cryo-electron microscopy (cryo-EM) analysis revealed either one or two polymerases bound to the clamp and DNA. In the one-polymerase complex, the DNA threads perpendicularly through the clamp, supporting processive synthesis. In contrast, the two-polymerase complex displays a markedly tilted DNA orientation, impeding sliding and representing exchange intermediates. Three distinct conformational states of the two-polymerase complex define a multistep exchange mechanism. To our knowledge, these findings provide the first molecular-level view of replicative polymerase exchange.

PubMed: 41459747
DOI: 10.1093/nar/gkaf1359

実験手法

ELECTRON MICROSCOPY (3.7 Å)