7TO3

Structure of Enterobacter cloacae Cap2-CdnD02 2:2 complex

Summary for 7TO3

• Entry DOI: 10.2210/pdb7to3/pdb
• EMDB information: 26028
• Descriptor: Cap2, Cyclic AMP-AMP-GMP synthase, ADENOSINE MONOPHOSPHATE, ... (6 entities in total)
• Functional Keywords: cbass, ubiquitin e1/e2, bacterial anti-phage defense, cgas, transferase
• Biological source: Enterobacter cloacae; More
• Total number of polymer chains: 4
• Total formula weight: 227723.99

Authors

Gu, Y.,Ye, Q.,Ledvina, H.E.,Quan, Y.,Lau, R.K.,Zhou, H.,Whiteley, A.T.,Corbett, K.D. (deposition date: 2022-01-22, release date: 2023-01-11, Last modification date: 2023-04-26)

Primary citation

Ledvina, H.E.,Ye, Q.,Gu, Y.,Sullivan, A.E.,Quan, Y.,Lau, R.K.,Zhou, H.,Corbett, K.D.,Whiteley, A.T.
An E1-E2 fusion protein primes antiviral immune signalling in bacteria.
Nature, 616:319-325, 2023

PubMed Abstract: In all organisms, innate immune pathways sense infection and rapidly activate potent immune responses while avoiding inappropriate activation (autoimmunity). In humans, the innate immune receptor cyclic GMP-AMP synthase (cGAS) detects viral infection to produce the nucleotide second messenger cyclic GMP-AMP (cGAMP), which initiates stimulator of interferon genes (STING)-dependent antiviral signalling. Bacteria encode evolutionary predecessors of cGAS called cGAS/DncV-like nucleotidyltransferases (CD-NTases), which detect bacteriophage infection and produce diverse nucleotide second messengers. How bacterial CD-NTase activation is controlled remains unknown. Here we show that CD-NTase-associated protein 2 (Cap2) primes bacterial CD-NTases for activation through a ubiquitin transferase-like mechanism. A cryo-electron microscopy structure of the Cap2-CD-NTase complex reveals Cap2 as an all-in-one ubiquitin transferase-like protein, with distinct domains resembling eukaryotic E1 and E2 proteins. The structure captures a reactive-intermediate state with the CD-NTase C terminus positioned in the Cap2 E1 active site and conjugated to AMP. Cap2 conjugates the CD-NTase C terminus to a target molecule that primes the CD-NTase for increased cGAMP production. We further demonstrate that a specific endopeptidase, Cap3, balances Cap2 activity by cleaving CD-NTase-target conjugates. Our data demonstrate that bacteria control immune signalling using an ancient, minimized ubiquitin transferase-like system and provide insight into the evolution of the E1 and E2 machinery across domains of life.

PubMed: 36755092
DOI: 10.1038/s41586-022-05647-4

Experimental method

ELECTRON MICROSCOPY (2.74 Å)