RsmYZ

RsmYZ refers to two closely related small regulatory RNAs, commonly named RsmY and RsmZ, found in several Pseudomonas species and related Gammaproteobacteria. They are central components of the Gac/Rsm regulatory network, acting as antagonists of the global RNA-binding proteins RsmA and RsmN.

Function and mechanism

RsmY and RsmZ are trans-encoded small RNAs that modulate gene expression by binding to RsmA and RsmN proteins. When produced, they sequester these proteins, reducing their ability to interact with target mRNAs. This titration alters the stability and translation of a broad set of transcripts, thereby influencing diverse cellular processes. The resulting changes can affect virulence factor production, secretion systems, metabolism, motility, and biofilm formation, among other traits.

Regulation

Expression of rsmY and rsmZ is controlled by the GacS/GacA two-component system in response to environmental cues and population-density signals. The regulatory RNA transcripts are produced in response to these signals and then act to modulate the activity of RsmA/RsmN, forming a feedback-rich circuit that enables the bacterium to adapt to changing conditions.

Genomic and evolutionary context

RsmY and RsmZ are encoded by separate genes within the chromosome of their host species. The two RNAs may vary in sequence and expression levels among species but share a common role as antagonists of RsmA/RsmN. They often contain conserved GGA motifs that facilitate binding by the RsmA/RsmN proteins.

Significance

As key players in post-transcriptional regulation, RsmY and RsmZ contribute to bacterial adaptability and pathogenic potential. They are a focus of studies on virulence regulation, biofilm development, and the broader RNA-based regulatory networks in Pseudomonas and related bacteria.