9ASI

Cryo-EM structure of the active Lactococcus lactis Csm bound to target in pre-cleavage stage

9ASI の概要

• エントリーDOI: 10.2210/pdb9asi/pdb
• EMDBエントリー: 43815
• 分子名称: CRISPR-associated protein Csm4, ADENOSINE MONOPHOSPHATE, CRISPR system Cms endoribonuclease Csm3, ... (10 entities in total)
• 機能のキーワード: type iii-a crispr-cas, csm, cyclic oligoadenylate synthesis, rna binding protein-rna complex, rna binding protein/rna
• 由来する生物種: Lactococcus lactis subsp. lactis; 詳細
• タンパク質・核酸の鎖数: 12
• 化学式量合計: 333248.08

構造登録者

Wang, B.,Goswami, H.N.,Li, H. (登録日: 2024-02-25, 公開日: 2024-08-14, 最終更新日: 2024-10-30)

主引用文献

Goswami, H.N.,Ahmadizadeh, F.,Wang, B.,Addo-Yobo, D.,Zhao, Y.,Whittington, A.C.,He, H.,Terns, M.P.,Li, H.
Molecular basis for cA6 synthesis by a type III-A CRISPR-Cas enzyme and its conversion to cA4 production.
Nucleic Acids Res., 52:10619-10629, 2024

PubMed Abstract: The type III-A (Csm) CRISPR-Cas systems are multi-subunit and multipronged prokaryotic enzymes in guarding the hosts against viral invaders. Beyond cleaving activator RNA transcripts, Csm confers two additional activities: shredding single-stranded DNA and synthesizing cyclic oligoadenylates (cOAs) by the Cas10 subunit. Known Cas10 enzymes exhibit a fascinating diversity in cOA production. Three major forms-cA3, cA4 and cA6have been identified, each with the potential to trigger unique downstream effects. Whereas the mechanism for cOA-dependent activation is well characterized, the molecular basis for synthesizing different cOA isoforms remains unclear. Here, we present structural characterization of a cA6-producing Csm complex during its activation by an activator RNA. Analysis of the captured intermediates of cA6 synthesis suggests a 3'-to-5' nucleotidyl transferring process. Three primary adenine binding sites can be identified along the chain elongation path, including a unique tyrosine-threonine dyad found only in the cA6-producing Cas10. Consistently, disrupting the tyrosine-threonine dyad specifically impaired cA6 production while promoting cA4 production. These findings suggest that Cas10 utilizes a unique enzymatic mechanism for forming the phosphodiester bond and has evolved distinct strategies to regulate the cOA chain length.

PubMed: 38989619
DOI: 10.1093/nar/gkae603

実験手法

ELECTRON MICROSCOPY (2.79 Å)