NixI

Contributors: Marian Dominguez-Mirazo

Description

Phage-inducible chromosomal island-like elements (PLEs) are chromosomally-integrated phage parasites described in Vibrio cholerae () . PLEs excise in response to infection by phage ICP1 and halt its progeny production. PLE halts ICP1 infection by redirecting virion packaging and interfering with ICP1 genome replication () . NixI is a PLE-encoded nuclease that nicks the ICP1 genome at specific sites preventing transition to the rolling circle replication (RCR) () .

Molecular mechanisms

The NixI endonuclease cleaves the ICP1 genome at the GNAANCTT motif () . It creates nicks and does not cause double-stranded breaks () .

Example of genomic structure

The NixI is composed of 2 proteins: NixI and Stix.

Here is an example found in the RefSeq database:

The NixI system in Apilactobacillus kunkeei (GCF_001314945.1, NZ_CP012920) is composed of 1 protein: NixI (WP_158520138.1)

Distribution of the system among prokaryotes

Among the 22,803 complete genomes of RefSeq, the NixI is detected in 8 genomes (0.04 %).

The system was detected in 5 different species.

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

Structure

NixI

Example 1

Experimental validation

      
graph LR;
    Legault_2022[LeGault et al., 2022] --> Origin_0
    Origin_0[Vibrio cholerae 
WP_045177897.1] --> Expressed_0[Vibrio cholerae]
    Expressed_0[Vibrio cholerae] ----> ICP1
    subgraph Title1[Reference]
        Legault_2022
end
    subgraph Title2[System origin]
        Origin_0
end
    subgraph Title3[Expression species]
        Expressed_0
end
    subgraph Title4[Protects against]
        ICP1
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

10.1093/nar/gkac002
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10.7554/eLife.53200
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10.1093/nar/gkz1005
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