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Mode of Action (MoA)
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cleave and inactivate 3′3′-cGAMP and related molecules
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Evidence
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Acb5 was identified as an anti-CBASS enzyme through growth and plaque assays showing that co-expression of Acb5 with a CBASS system from E. albertii restored infectivity of phages T2 and Bas60. In phage-infected cells expressing the CD-NTase enzyme, co-expression of Acb5 led to complete loss of detectable 3′3′-cGAMP, measured by ELISA (ECO_0000267). Thin-layer chromatography (ECO_0000140) and HPLC ( ECO_0001272) analyses demonstrated enzymatic cleavage of 3′3′-cGAMP by Acb5 into 2′3′-cAMP and 2′3′-cGMP, with similar partial activity against 3′3′-cUA. AlphaFold3 models predicted conserved interfacial binding pockets for both substrate and cleavage products, stabilized by conserved residues (e.g., R10, H61, W38), whose alanine mutations abolished anti-defense function.
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MoA Category
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degrades or sequesters molecules utilised by host defence systems
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Subtype(s) of the defence system(s) inhibited by the protein
Defence Subtype
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Escherichia albertii MOD1-EC1698 type I CBASS
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Relevant publication(s)
DOI
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10.1101/2025.07.12.664507
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Other components of the anti-defence system
Multicomponent System
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-
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Known structure in PDB
PDB ID
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-
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Genome(s) encoding the protein
Protein Source
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Metagenomics data (IMG_VR ID: IMGVR_UViG_3300024284_000007)
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Defence system(s) inhibited by the protein
Defences
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CBASS
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