7TGI

Single-domain VHH intrabodies neutralize ricin toxin

7TGI の概要

• エントリーDOI: 10.2210/pdb7tgi/pdb
• 関連するPDBエントリー: 7TGF
• 分子名称: Ricin chain A, VHH antibody, CHLORIDE ION, ... (5 entities in total)
• 機能のキーワード: ricin toxin, vhh antibody, immune system, immune system-toxin complex, immune system/toxin
• 由来する生物種: Ricinus communis (castor bean); 詳細
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 44820.35

構造登録者

Rudolph, M.J. (登録日: 2022-01-07, 公開日: 2022-10-12, 最終更新日: 2023-10-18)

主引用文献

Czajka, T.F.,Vance, D.J.,Davis, S.,Rudolph, M.J.,Mantis, N.J.
Single-domain antibodies neutralize ricin toxin intracellularly by blocking access to ribosomal P-stalk proteins.
J.Biol.Chem., 298:101742-101742, 2022

PubMed Abstract: During ricin intoxication in mammalian cells, ricin's enzymatic (RTA) and binding (RTB) subunits disassociate in the endoplasmic reticulum. RTA is then translocated into the cytoplasm where, by virtue of its ability to depurinate a conserved residue within the sarcin-ricin loop (SRL) of 28S rRNA, it functions as a ribosome-inactivating protein. It has been proposed that recruitment of RTA to the SRL is facilitated by ribosomal P-stalk proteins, whose C-terminal domains interact with a cavity on RTA normally masked by RTB; however, evidence that this interaction is critical for RTA activity within cells is lacking. Here, we characterized a collection of single-domain antibodies (VHs) whose epitopes overlap with the P-stalk binding pocket on RTA. The crystal structures of three such VHs (V9E1, V9F9, and V9B2) in complex with RTA revealed not only occlusion of the ribosomal P-stalk binding pocket but also structural mimicry of C-terminal domain peptides by complementarity-determining region 3. In vitro assays confirmed that these VHs block RTA-P-stalk peptide interactions and protect ribosomes from depurination. Moreover, when expressed as "intrabodies," these VHs rendered cells resistant to ricin intoxication. One VH (V9F6), whose epitope was structurally determined to be immediately adjacent to the P-stalk binding pocket, was unable to neutralize ricin within cells or protect ribosomes from RTA in vitro. These findings are consistent with the recruitment of RTA to the SRL by ribosomal P-stalk proteins as a requisite event in ricin-induced ribosome inactivation.

PubMed: 35182523
DOI: 10.1016/j.jbc.2022.101742

実験手法

X-RAY DIFFRACTION (2.104 Å)