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2  structures 987  species 0  interactions 1337  sequences 16  architectures

Clan: AbiEI (CL0578)


Antitoxin of Type IV toxin-antitoxin, Abi system Add an annotation

AbiEI is a famaily of bacterial toxins that are both the cognate antitoxins of the bacterial toxin-antitoxin system of type IV and part of the innate immunity system against phage infection. Bacterial abortive infection (Abi) systems are the apoptosis sytems of bacteria that ensue after phage infection to prevent further viral replication. This superfamily of antitoxins are derived from the orthologous clusters COG5340 and COG4861. They all appear to be transcriptional regulators and in each case their cognate toxin is the nucleotidyal transferase, AbiEii, Pfam:PF08843, derived from COG2253 and COG4849. Each has an N-terminal winged-helix-turn-helix domain required for repression of abiE transcription (these may or ay not be modelled in the families), and an uncharacterized bi-functional C-terminal domain that is necessary for transcriptional repression and is sufficient for neutralising the toxin [1].

This clan contains 3 families and the total number of domains in the clan is 1337. The clan was built by P Coggill.

Literature references

  1. Dy RL, Przybilski R, Semeijn K, Salmond GP, Fineran PC;, Nucleic Acids Res. 2014;42:4590-4605.: A widespread bacteriophage abortive infection system functions through a Type IV toxin-antitoxin mechanism. PUBMED:24465005 EPMC:24465005


This clan contains the following 3 member families:

AbiEi_1 AbiEi_2 AbiEi_3

Domain organisation

Below is a listing of the unique domain organisations or architectures from this clan. More...

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The table below shows the number of occurrences of each domain throughout the sequence database. More...

Pfam family Num. domains Alignment
AbiEi_3 (PF11459) 516 (38.6%) View
AbiEi_1 (PF09407) 478 (35.8%) View
AbiEi_2 (PF09952) 343 (25.7%) View
Total: 3 Total: 1337 Clan alignment

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Family relationships

This diagram shows the relationships between members of this clan. More...

Species distribution

Tree controls


This tree shows the occurrence of the domains in this clan across different species. More...



For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the MSD group, to allow us to map Pfam domains onto UniProt three-dimensional structures. The table below shows the mapping between the Pfam families in this clan, the corresponding UniProt entries, and the region of the three-dimensional structures that are available for that sequence.

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