Originally found in a high throughput shotgun cloning of bacterial fragments in E. coli looking for Toxin-Antitoxin pairs. PsyrTA is composed of two proteins, PsyrT, the toxin, is a RecQ family DNA helicase, and PsyrA, the antitoxin, was shown to be a Nucleotide-binding protein. Note that that system is sometimes called RqlHI :ref{doi=10.1371/journal.ppat.1005317}, where RqlH refers to PsyrT and RqlI to PsyrA
## Molecular mechanisms
from :ref{doi=10.1016/j.molcel.2013.02.002} :
> The psyrT shares homology with domains of the RecQ helicase,
> a family of proteins implicated in DNA repair (Bernstein et al.,
> 2010); and the antitoxin of the same system, psyrA, has a nucle-
> otide binding domain (COG0758) that was previously described
> in proteins involved in DNA uptake
from :ref{doi=10.1016/j.chom.2022.09.017} :
> Both systems encode an antitoxin
> with homology to DprA, a single-stranded DNA (ssDNA)-binding
> protein known to be involved in DNA transformation (Mortier-
> Barrière et al., 2007). The toxin contains a phosphoribosyl trans-
> ferase (PRTase) domain, which was previously found in effectors
> of retron abortive infection systems "
## Example of genomic structure
The PsyrTA system is composed of 2 proteins: PsyrT and, PsyrA.
