FS_HP

Contributors: Marian Dominguez-Mirazo

Description

PICIs (Phage-inducible chromosomal islands) are highly mobile genetic elements that reside in the bacterial chromosome in the absence of a helper phage. Following infection by the helper phage, PICIs excise and replicate by hijacking the helper phage machinery. The FS_HP system was discovered in *E. fergusonii through the manual search for immune systems in flanking regions of gram-negative PICIs () . It is composed of a single protein with a hypothetical domain, from which it derives the HP part of its name. The system showcases a broad defense spectrum. It was tested against 15 lytic phages in 3 gram-negative bacteria and protected the bacterial host against 3 unrelated phages in 2 different bacteria species. FS_HP also blocked the formation of phage particles upon induction of the P22 S. enterica prophage. Therefore, the system can block phage in both lytic and lysogenic life cycles. It was also shown to reduce the production of transducing particles.

Molecular mechanisms

As far as we are aware, the molecular mechanism is unknown.

Example of genomic structure

The FS_HP is composed of 1 protein: HP.

Here is an example found in the RefSeq database:

The FS_HP system in Escherichia coli (GCF_016944735.1, NZ_CP063511) is composed of 1 protein: HP (WP_227456581.1)

Distribution of the system among prokaryotes

Among the 22,803 complete genomes of RefSeq, the FS_HP is detected in 93 genomes (0.41 %).

The system was detected in 29 different species.

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

Structure

FS_HP

Example 1

Experimental validation

      
graph LR;
    Fillol-Salom_2022[Fillol-Salom et al., 2022] --> Origin_0
    Origin_0[Escherichia fergusonii 
QML19489.1] --> Expressed_0[Escherichia coli]
    Expressed_0[Escherichia coli] ----> HK578
    Fillol-Salom_2022[Fillol-Salom et al., 2022] --> Origin_0
    Origin_0[Escherichia fergusonii 
QML19489.1] --> Expressed_1[Salmonella enterica]
    Expressed_1[Salmonella enterica] ----> P22 & ES18
    subgraph Title1[Reference]
        Fillol-Salom_2022
end
    subgraph Title2[System origin]
        Origin_0
        Origin_0
end
    subgraph Title3[Expression species]
        Expressed_0
        Expressed_1
end
    subgraph Title4[Protects against]
        HK578
        P22
        ES18
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

10.1016/j.cell.2022.07.014
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