PrrC

Contributors: Ernest Mordret

Description

The PrrC system protects bacteria against phages via an abortive infection. It is composed of a single effector protein but relies on the presence of a full type Ic restriction-modification system in the vicinity. PrrC proteins are therefore typically found embedded in a larger RM system.

Molecular mechanism

The effector protein prrC complements a RM system by cutting tRNALys in the anticodon loop, upstream of the wobble nucleotide and causes the arrest of phage protein synthesis and phage growth. PrrC serves as a guardian of the activity of EcoprrI, which can be inactivated by the Stp peptide of phage T4 at the beginning of infection. Inactivation of EcoprrI by Stp induces a conformation change that in turn activates PrrC, releasing its nuclease activity and stalling host and phage growth () . Because it sabotages the host's translation machinery, PrrC is considered to be an abortive infection system.

Example of genomic structure

The PrrC is composed of the PrrC protein and a type I restriction-modification system.

Here is an example found in the RefSeq database:

The PrrC system in Parazoarcus communis (GCF_003111645.1, NZ_CP022187) is composed of 4 proteins Type_I_REases (WP_108949925.1) Type_I_S (WP_108949926.1) PrrC (WP_108949927.1) Type_I_MTases (WP_108949929.1)

Distribution of the system among prokaryotes

Among the 22,803 complete genomes of RefSeq, the PrrC is detected in 705 genomes (3.09 %).

The system was detected in 309 different species.

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

Structure

PrrC

Example 1

RM

Example 1

Experimental validation

      
graph LR;
    Jabbar_1984[Jabbar and  Snyder, 1984] --> Origin_0
    Origin_0[Escherichia coli 
WP_012954793.1, WP_012954794.1,
WP_012954795.1, WP_012954796.1] --> Expressed_0[Escherichia coli]
    Expressed_0[Escherichia coli] ----> Lambda & T4 & Dec8
    subgraph Title1[Reference]
        Jabbar_1984
end
    subgraph Title2[System origin]
        Origin_0
end
    subgraph Title3[Expression species]
        Expressed_0
end
    subgraph Title4[Protects against]
        Lambda
        T4
        Dec8
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

10.1006/jmbi.1995.0343
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