dCTPdeaminase
Description
dCTPdeaminase is a family of systems. dCTPdeaminase from Escherichia coli has been shown to provide resistance against various lytic phages when expressed heterologously in another Escherichia coli by degrading the pool of dCTP available for phage DNA replication. This system is mostly found in Proteobacteria but a few examples also exist in Acidobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria, Firmicutes, Planctomyces, and Verrucomicrobia. Those systems can be found in plasmids (around 8%).
Mechanism
When activated by a phage infection, dCTPdeaminase will convert deoxycytidine (dCTP/dCDP/dCMP) into deoxyuridine. This action will deplete the pool of CTP nucleotide necessary for the phage replication and will stop the infection. The trigger for dCTPdeaminase may be linked to the shutoff of RNAP ($\sigma$ S-dependent host RNA polymerase) that occurs during phage infections.
Example of genomic structure
The dCTPdeaminase is composed of 1 protein: dCTPdeaminase.
Here is an example found in the RefSeq database:
The dCTPdeaminase system in Pseudomonas entomophila (GCF_023277925.1, NZ_CP063832) is composed of 1 protein: dCTPdeaminase (WP_248918739.1)