rsmY

RsmY is a small regulatory RNA (sRNA) found in several Gram-negative bacteria, most notably Pseudomonas species, where it forms part of the RsmY/RsmZ (and sometimes RsmX) family. These sRNAs are typically 150–230 nucleotides long and adopt multiple stem-loop structures that display conserved GGA motifs in their loops. RsmY functions as a decoy for RNA-binding proteins of the RsmA/CsrA family; by sequestering RsmA (and related proteins such as RsmE), it relieves RsmA-mediated repression of target mRNAs, thereby altering translation and stability of numerous transcripts involved in metabolism, motility, quorum sensing, and virulence. In Pseudomonas aeruginosa, elevated levels of RsmY and RsmZ promote biofilm formation and suppress certain acute virulence traits through RsmA sequestration.

RsmY and its homologs are typically transcriptionally activated by the GacS/GacA two-component regulatory system, with GacS activating GacA to promote sRNA transcription. Expression can also be modulated by additional signaling pathways, including RetS and LadS, allowing the cell to adapt to environmental cues. The RsmY family is widely studied as part of the Gac/Rsm regulatory axis in Gram-negative bacteria, especially Pseudomonas species, and homologs have been observed in diverse organisms where they function to sequester CsrA/RsmA proteins. Detection and functional analysis commonly employ RNA-based methods such as Northern blotting or RNA sequencing, along with mutational or reporter assays targeting RsmA-regulated transcripts.