ジャーナル: Sci Adv / 年: 2024 タイトル: Structural basis for regulation of a CBASS-CRISPR-Cas defense island by a transmembrane anti-σ factor and its ECF σ partner. 著者: Diego Bernal-Bernal / David Pantoja-Uceda / Jorge Pedro López-Alonso / Alfonso López-Rojo / José Antonio López-Ruiz / Marisa Galbis-Martínez / Borja Ochoa-Lizarralde / Igor Tascón / ...著者: Diego Bernal-Bernal / David Pantoja-Uceda / Jorge Pedro López-Alonso / Alfonso López-Rojo / José Antonio López-Ruiz / Marisa Galbis-Martínez / Borja Ochoa-Lizarralde / Igor Tascón / Montserrat Elías-Arnanz / Iban Ubarretxena-Belandia / S Padmanabhan / 要旨: How CRISPR-Cas and cyclic oligonucleotide-based antiphage signaling systems (CBASS) are coordinately deployed against invaders remains unclear. We show that a locus containing two CBASS and one type ...How CRISPR-Cas and cyclic oligonucleotide-based antiphage signaling systems (CBASS) are coordinately deployed against invaders remains unclear. We show that a locus containing two CBASS and one type III-B CRISPR-Cas system, regulated by the transmembrane anti-σ DdvA and its cognate extracytoplasmic function (ECF) σ DdvS, can defend against a phage. Cryo-electron microscopy reveals DdvA-DdvS pairs assemble as arrow-shaped transmembrane dimers. Each DdvA periplasmic domain adopts a separase/craspase-type tetratricopeptide repeat (TPR)-caspase HetF-associated with TPR (TPR-CHAT) architecture with an incomplete His-Cys active site, lacking three α-helices conserved among CHAT domains. Each active site faces the dimer interface, raising the possibility that signal-induced caspase-like DdvA autoproteolysis in trans precedes RseP-mediated intramembrane proteolysis and DdvS release. Nuclear magnetic resonance reveals a DdvA cytoplasmic CHCC-type zinc-bound three-helix bundle that binds to DdvS σ and σ domains, undergoing σ-induced helix extension to trap DdvS. Altogether, we provide structural-mechanistic insights into membrane anti-σ-ECF σ regulation of an antiviral CBASS-CRISPR-Cas defense island.