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Mode of Action (MoA)
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hyperphosphorylates E. coli early proteins, with a preference for DNA/RNA-binding proteins including DNA-targeting defence systems.
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Evidence
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T7 protein kinase (T7K) was identified as a broad-spectrum anti-defense factor through infection assays comparing wild-type T7 and a Δ0.7 mutant lacking the kinase. Deletion of T7K reduced infectivity in E. coli strains expressing DNA-targeting defense systems such as Retron-Eco9 and DarTG1 (ECO_0001175). Mass spectrometry (ECO_0001096) during infection revealed extensive phosphorylation of host and phage proteins, with Retron-Eco9's RcaT toxin and DarTG1’s DarT toxin among the stoichiometrically modified targets. Phosphomimetic mutations at key T7K-targeted sites (e.g., RcaT S155D, S254D; DarT T103D) abolished defense activity, confirming functional inactivation via phosphorylation. T7K’s C-terminal domain was shown to bind DNA, directing its otherwise promiscuous kinase activity to nucleic acid-binding defense components.
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MoA Category
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adds a post-translational modification and deactivates bacterial defence
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Subtype(s) of the defence system(s) inhibited by the protein
Defence Subtype
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Escherichia coli type II Retron (Eco9) and type IV TA system DarTG
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Relevant publication(s)
DOI
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10.1101/2024.12.20.629319
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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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Enterobacteria phage T4
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Defence system(s) inhibited by the protein
Defences
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Retron,
TA
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View homologs from eukaryotic dsDNA viruses
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