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Mode of Action (MoA)
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removes ADP-ribose modifications from phage DNA.
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Evidence
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AdfN was identified via recombination experiments between DarTG1-sensitive RB69 and resistant T4/T2 phages. Mapping of recombinant genomes pinpointed a 3′ region of gene 30.3 (renamed adfN) that correlates with DarTG1 resistance. Unlike RB69, which encodes a truncated AdfN protein due to a frameshift mutation, resistant phages encode full-length AdfN. Deletion of adfN in T2 or T4 rendered both phages sensitive to DarTG1, while ectopic expression of AdfN in E. coli restored RB69 infectivity in the presence of DarTG1. Point mutations in conserved catalytic residues (E36A, K43A) or truncation at the RB69 stop codon site impaired activity, indicating the requirement for enzymatic function. In vitro dot blot assays confirmed that purified AdfN protein removes ADP-ribose from DNA, directly counteracting DarT1’s toxic modification. Notably, AdfN did not interact with DarT1 in a two-hybrid assay and failed to protect E. coli from DarT1 toxicity in the absence of phage, suggesting that AdfN acts via enzymatic detoxification of modified DNA, not toxin binding, and requires phage context for full activity.
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MoA Category
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uncategorised
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Subtype(s) of the defence system(s) inhibited by the protein
Defence Subtype
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Escherichia coli type IV TA system DarTG
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Relevant publication(s)
DOI
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10.1101/2024.07.11.602962,
10.1038/s41467-025-56887-7
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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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T4-like phages
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Defence system(s) inhibited by the protein
Defences
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TA
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