Wadjet

Contributors: Florian Tesson

Description

Wadjet is a defense system discovered in 2018 () . This system is named after the goddess Wadjet matron and protector of the lower Egypt.

This system was discovered using the defense island concept () . However, this system do not show any activity against phages, this system provides a resistance against plasmid transformation (, ) .

This system is composed of 4 genes: JetA, JetB, JetC and JetD. JetA, JetB and JetC were found to be similar to respectively MukF, MukE and MukB which are housekeeping genes (, ) . Notably, JetC (similar to MukB) is a SMC domain-containing protein.

Molecular mechanism

Wadjet was shown to possess an anti-plasmid activity via close, circular DNA cleavage () . JetA, B and C were shown to form a complex which acts as a sensor detecting the foreign DNA using topology sensing. The JetD protein forms a homodimeric endonuclease that cleaves double-stranded DNA. JetD needs to be in contact with the JetABC complex to be able to cleave DNA.

The precise mechanism suggested by the authors () is that the JetABC complex binds to the DNA and extrudes DNA loops similarly to Muk and other SMC proteins (, ) . These loops are then cleaved by JetD.

Example of genomic structure

A total of 3 subsystems have been described for the Wadjet system.

Here is some examples found in the RefSeq database:

The Wadjet_I system in Corynebacterium humireducens (GCF_000819445.1, NZ_CP005286) is composed of 4 proteins JetA_I (WP_040084540.1) JetB_I (WP_052437638.1) JetC_I (WP_040084541.1) JetD_I (WP_040084542.1)

The Wadjet_II system in Streptomyces paludis (GCF_003344965.1, NZ_CP031194) is composed of 4 proteins JetA_II (WP_114665121.1) JetB_II (WP_114660010.1) JetC_II (WP_114660011.1) JetD_II (WP_228447139.1)

The Wadjet_III system in Cytobacillus spongiae (GCF_021390075.1, NZ_CP089997) is composed of 4 proteins JetD_III (WP_233811322.1) JetA_III (WP_233811323.1) JetB_III (WP_233811324.1) JetC_III (WP_233811325.1)

Distribution of the system among prokaryotes

Among the 22,803 complete genomes of RefSeq, the Wadjet is detected in 2351 genomes (10.31 %).

The system was detected in 1467 different species.

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

Structure

Experimentally determined structure

From () in Pseudomonas aeruginosa PA14:

Wadjet_I

Example 1

Wadjet_II

Example 1

Wadjet_III

Example 1

References

10.1126/science.aar4120
no authors
no containerTitle ()
10.1016/j.molcel.2022.09.008
no authors
no containerTitle ()
10.1098/rstb.2004.1606
no authors
no containerTitle ()
10.1126/science.abm4012
no authors
no containerTitle ()
10.1126/science.abb0981
no authors
no containerTitle ()