9QVJ

Crystal structure of CtaG from Ruminiclostridium cellulolyticum (P2(1)-medium)

9QVJ の概要

• エントリーDOI: 10.2210/pdb9qvj/pdb
• 関連するPDBエントリー: 9QUZ
• 分子名称: Butirosin biosynthesis protein H N-terminal domain-containing protein, GLYCEROL (3 entities in total)
• 機能のキーワード: amide bond formation; antibiotics; biosynthesis; carrier proteins; enzymes, nonribosomal peptide synthetases, ligase
• 由来する生物種: Ruminiclostridium cellulolyticum
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 74682.02

構造登録者

Gude, F.,Bohne, A.,Dell, M.,Franke, J.,Dunbar, K.L.,Groll, M.,Hertweck, C. (登録日: 2025-04-11, 公開日: 2025-10-01, 最終更新日: 2026-02-18)

主引用文献

Gude, F.,Bohne, A.,Dell, M.,Franke, J.,Dunbar, K.L.,Groll, M.,Hertweck, C.
Distal peptide elongation by a protease-like ligase and two distinct carrier proteins.
Chem, 12:None-None, 2026

PubMed Abstract: Closthioamide (CTA) is a potent antibiotic with a unique polythioamide scaffold produced by . Unlike classical non-ribosomal peptide synthetases (NRPSs), which use modular adenylation and condensation domains, CTA biosynthesis proceeds through non-canonical standalone enzymes. Central to this process is the papain-like ligase CtaG, which catalyzes amide bond formation between two distinct peptidyl carrier proteins (PCPs): CtaH, presenting para-hydroxybenzoic acid (PHBA), and CtaE, carrying a tri-β-alanine ((βAla)) chain. Using biochemical assays, chemical probes, crystallography, and mutational analysis, we show that CtaG operates via a ping-pong mechanism involving an enzyme-bound intermediate. A single substrate tunnel mediates directional transfer, enabling distal chain elongation that mirrors solid-phase peptide synthesis. Structure-based genome mining revealed homologous enzymes in the biosynthetic pathways of petrobactin, butirosin, and methylolanthanin. Together, our findings uncover a previously overlooked class of thiotemplated ligases and provide a mechanistic blueprint for engineering ribosome-independent peptide assembly lines.

PubMed: 41641319
DOI: 10.1016/j.chempr.2025.102740

実験手法

X-RAY DIFFRACTION (1.55 Å)