SgrS RNA

SgrS (sugar transport-related sRNA, previously named ryaA)^[1] is a 227 nucleotide small RNA that is activated by SgrR in Escherichia coli during glucose-phosphate stress. The nature of glucose-phosphate stress is not fully understood, but is correlated with intracellular accumulation of glucose-6-phosphate.^[2] SgrS helps cells recover from glucose-phosphate stress by base pairing with ptsG mRNA (encoding the glucose transporter) and causing its degradation in an RNase E dependent manner.^[3][4] Base pairing between SgrS and ptsG mRNA also requires Hfq, an RNA chaperone frequently required by small RNAs that affect their targets through base pairing.^[5] The inability of cells expressing sgrS to create new glucose transporters leads to less glucose uptake and reduced levels of glucose-6-phosphate. SgrS is an unusual small RNA in that it also encodes a 43 amino acid functional polypeptide, SgrT, which helps cells recover from glucose-phosphate stress by preventing glucose uptake. The activity of SgrT does not affect the levels of ptsG mRNA of PtsG protein.^[2] It has been proposed that SgrT exerts its effects through regulation of the glucose transporter, PtsG.^[6][7]

SgrS RNA
Predicted secondary structure and sequence conservation of SgrS
Identifiers
Symbol	SgrS
Rfam	RF00534
Other data
RNA type	Gene; antisense
Domain(s)	Bacteria
GO	GO:0032057 GO:0043488 GO:0030371
SO	SO:0000655
PDB structures	PDBe

SgrS was originally discovered in E. coli but homologues have since been identified in other Gammaproteobacteria such as Salmonella enterica and members of the genus Citrobacter.^[8] A comparative genomics based target prediction approach that employs these homologs, has been developed and was used to predict the SgrS target, ptsI (b2416), which was subsequently verified experimentally.^[9]