8FMG

Structure of CBASS Cap5 from Pseudomonas syringae as an activated tetramer with the cyclic dinucleotide 3'2'-c-diAMP ligand (3 tetramers in the AU)

Summary for 8FMG

• Entry DOI: 10.2210/pdb8fmg/pdb
• Descriptor: SAVED domain-containing protein, ZINC ION, MAGNESIUM ION, ... (5 entities in total)
• Functional Keywords: cyclic dinucleotide, bacterial immunity, cbass, cap5 effector dna endonuclease, viral defense, immune system
• Biological source: Pseudomonas syringae
• Total number of polymer chains: 12
• Total formula weight: 522232.67

Authors

Rechkoblit, O.,Kreitler, D.F.,Aggarwal, A.K. (deposition date: 2022-12-23, release date: 2024-02-07, Last modification date: 2024-05-29)

Primary citation

Rechkoblit, O.,Sciaky, D.,Kreitler, D.F.,Buku, A.,Kottur, J.,Aggarwal, A.K.
Activation of CBASS Cap5 endonuclease immune effector by cyclic nucleotides.
Nat.Struct.Mol.Biol., 31:767-776, 2024

PubMed Abstract: The bacterial cyclic oligonucleotide-based antiphage signaling system (CBASS) is similar to the cGAS-STING system in humans, containing an enzyme that synthesizes a cyclic nucleotide on viral infection and an effector that senses the second messenger for the antiviral response. Cap5, containing a SAVED domain coupled to an HNH DNA endonuclease domain, is the most abundant CBASS effector, yet the mechanism by which it becomes activated for cell killing remains unknown. We present here high-resolution structures of full-length Cap5 from Pseudomonas syringae (Ps) with second messengers. The key to PsCap5 activation is a dimer-to-tetramer transition, whereby the binding of second messenger to dimer triggers an open-to-closed transformation of the SAVED domains, furnishing a surface for assembly of the tetramer. This movement propagates to the HNH domains, juxtaposing and converting two HNH domains into states for DNA destruction. These results show how Cap5 effects bacterial cell suicide and we provide proof-in-principle data that the CBASS can be extrinsically activated to limit bacterial infections.

PubMed: 38321146
DOI: 10.1038/s41594-024-01220-x

Experimental method

X-RAY DIFFRACTION (1.79 Å)