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Mode of Action (MoA)
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the mechanism is not clear, apart from its role in regulating the expression of ardA and ardB.
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Evidence
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ArdK was identified as a transcriptional regulator of the antirestriction genes ardA and ardB through promoter activity assays and stability experiments using plasmid derivatives with and without upstream regulatory sequences. Expression of ardB from constructs containing the upstream conserved CUP region (e.g., pCAT66-4) resulted in plasmid instability unless ArdK was provided in trans, suggesting repression of a strong promoter (P2) by ArdK. Promoter probe assays showed that ArdK specifically repressed P2 activity but not P1. Maxicell experiments confirmed expression of a 15-kDa ArdK protein from the ardK gene. Combined with ArdR, ArdK completely abolished promoter activity from CUP sequences upstream of ardB and ardA, indicating coordinated repression at the transcriptional level. Sequence homology in the regulatory regions of ardA and ardB (94% identity) further supports ArdK’s dual role in their regulation.
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MoA Category
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unknown
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Subtype(s) of the defence system(s) inhibited by the protein
Defence Subtype
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Escherichia coli type I RM
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Relevant publication(s)
DOI
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10.1128/jb.175.15.4843-4850.1993
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Other components of the anti-defence system
Multicomponent System
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ardr;
arda;
ardc
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Known structure in PDB
PDB ID
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7BBQ
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Genome(s) encoding the protein
Protein Source
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Plasmid pKM101
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Defence system(s) inhibited by the protein
Defences
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RM
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