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Mode of Action (MoA)
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bind and sequester the TIR-produced signaling molecules 3′cADPR and His-ADPR
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Evidence
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Sequestin proteins were identified as anti-Thoeris defense factors through infection assays where co-expression of Sequestin with the type I Thoeris system in Bacillus subtilis restored phage SBSphiJ infectivity, leading to culture collapse and plaque formation. When Sequestin genes were engineered into the SBSphiJ phage genome, infectivity was similarly restored in Thoeris-expressing cells, confirming functional inactivation. NADase assays showed that lysates from Sequestin-expressing infected cells failed to activate ThsA, indicating depletion of the 3′cADPR immune signal. Biochemical binding was demonstrated by size-exclusion chromatography (ECO_0000325) and HPLC (ECO_0001272), where Sequestin bound and removed 3′cADPR from solution, with chloroform denaturation releasing the intact molecule. AlphaFold3 modeling placed 3′cADPR in conserved inter-protomer binding pockets, and alanine substitutions in key residues (E12, Q47, R61) abolished anti-defense function, confirming their role in sequestration (ECO_0006341).
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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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Bacillus cereus MSX-D12 type I Thoeris
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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_3300045988_056527)
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Defence system(s) inhibited by the protein
Defences
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Thoeris
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