AbiE

Contributors: Florian Tesson

Description

AbiE was discovered in 1995 on a Lactococcal plasmid () together with AbiF a homolog of AbiD](/defense-systems/abid).

AbiE is one of the so-called "Abi" systems for "Abortive infection" discovered in the 90's in research related to the dairy industry () . AbiE is classified as abortive infection in () .

AbiE is composed of two proteins: AbiEi and AbiEii. AbiEii is annotated as a nucleotidyltransferase.

Molecular mechanism

AbiE is a family of anti-phage defense systems. They act through a Toxin-Antitoxin mechanism, and are comprised of a pair of genes, with one gene being toxic while the other confers immunity to this toxicity () .

AbiEii is a GTP-binding nucleotidyltransferase (NTase) whose expression induces a reversible growth arrest () . On the other hand, AbiEi is a transcriptional autorepressor that binds to the promoter of the abiE operon. Based on these mechanisms, AbiE systems are classified as Type IV Toxin-Antitoxin systems, where the antitoxin and toxin are both proteins that do not directly interact with each other () .

Example of genomic structure

The AbiE is composed of 2 proteins: AbiEii and AbiEi.

Here is an example found in the RefSeq database:

The AbiE system in Halomonas piezotolerans (GCF_012427705.1, NZ_CP048602) is composed of 2 proteins AbiEi_3 (WP_231125510.1) AbiEii (WP_231125511.1)

Distribution of the system among prokaryotes

Among the 22,803 complete genomes of RefSeq, the AbiE is detected in 3708 genomes (16.26 %).

The system was detected in 1107 different species.

Proportion of genome encoding the AbiE system for the 14 phyla with more than 50 genomes in the RefSeq database.

Structure

AbiE

Example 1

Experimental validation

      
graph LR;
    Chopin_2005[Chopin et al., 2005] --> Origin_0
    Origin_0[lactococcal plasmid 
AAB52382.1, AAB52383.1] --> Expressed_0[lactococci]
    Expressed_0[lactococci] ----> 936
    subgraph Title1[Reference]
        Chopin_2005
end
    subgraph Title2[System origin]
        Origin_0
end
    subgraph Title3[Expression species]
        Expressed_0
end
    subgraph Title4[Protects against]
        936
end
    style Title1 fill:none,stroke:none,stroke-width:none
    style Title2 fill:none,stroke:none,stroke-width:none
    style Title3 fill:none,stroke:none,stroke-width:none
    style Title4 fill:none,stroke:none,stroke-width:none

    

References

10.1023/A:1002027321171
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10.1016/j.mib.2005.06.006
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10.1093/nar/gkt1419
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10.1128/aem.61.12.4321-4328.1995
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10.1016/j.mib.2023.102312
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