pfam19296: RelA_AH_RIS (This model is not part of the current CDD release)
RelA/SpoT, AH and RIS domains
This entry represents the alpha helical (AH) and Ribosome-InterSubunit (RIS) domains found in RelA/SpoT proteins, adjacent to the ACT domain. AH domain interacts with A/R tRNA and links the very C-terminal subdomains with TGS domain. The RIS domain is part of the binding interface between the C-terminal region and the ribosome, bridging the large and the small ribosomal subunits. RIS contains a four-stranded beta-sheet and a short alpha-helix. RelA/SpoT-homologue proteins (RHS) mediate the stringent response in bacteria which enables its metabolic adaptation under stress conditions. These enzymes synthesise the second messenger (p)ppGpp, which is a regulatory metabolite of the stringent response characterized by growth arrest and the modulation of gene expression in response to various nutritional stresses.
Jiyao W et al.(2023). "The conserved domain database in 2023.",