Toxin SymE-like (IPR014944)

Short name: Toxin_SymE-like

Overlapping homologous superfamilies


Domain relationships



SymE (SOS-induced yjiW gene with similarity to MazE) is an SOS-induced toxin. It inhibits cell growth, decreases protein synthesis and increases RNA degradation. It may play a role in the recycling of RNAs damaged under SOS response-inducing conditions. Its translation is repressed by the antisense RNA SymR, which acts as an antitoxin [PMID: 17376733, PMID: 17462020].

SymE belongs to type I toxin-antitoxin systems, but it does not show functional homology to other type I toxin proteins. Its function resembles that of type II toxins such as MazF, which can cleave mRNA independent of the ribosome. However, SymE has homology to the AbrB-fold superfamily proteins such as MazE, which act as transcriptional factors and antitoxins in various type II TA modules [PMID: 23131729]. It seems probable that SymE has evolved into an RNA cleavage protein with toxin-like properties from a transcription factor or antitoxin [PMID: 17462020].

GO terms

Biological Process

GO:0016070 RNA metabolic process

Molecular Function

GO:0003723 RNA binding
GO:0016788 hydrolase activity, acting on ester bonds

Cellular Component

GO:0005737 cytoplasm

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.