Dsr
Example of genomic structure
A total of 2 subsystems have been described for the Dsr system.
Here are some examples found in the RefSeq database:
The Dsr_I system in Pseudohalocynthiibacter aestuariivivens (GCF_011040495.1, NZ_CP049037) is composed of 1 protein: Dsr1 (WP_165194530.1)
The Dsr_II system in Deinococcus deserti (GCF_000020685.1, NC_012526) is composed of 1 protein: Dsr2 (WP_083764220.1)
Description
The defense-associated sirtuin (Dsr) is an abortive-type defense mechanism, that act through the degradation of bacterial NAD+ into ADPR, 30 min post infection. The depletion of NAD+ leads to metabolic and replication arrest of both the infected bacteria and the phage, limiting the transmission to the rest of the population. The system is activated by the interaction with the SPβ-like phages tails monomers. Additionaly, some escaper phages developped an anti DSR2 mechanism through the protein DASD1 which blocks the catalitic activity of DRS2. (N/A)
Molecular mechanisms
The DSR2 protein works at the tetramer with 4 catalitic site buried at the center. Upon infection by a targeted phage, monomers of the tube tail structure interacts with the hydrophobic pockets located at the CTD of each DSR2 protein of the tetramer. These interaction leads the reorganisation of the SIR2 domains and expose the NADpase sites, activating the complex. A phage escape strategie involves DSAD1, a competitive inhibitor of the DSR2/tail monomer interaction, that blocks the activation of the defense system. (N/A)