Carbon storage regulator A (CsrA) is an
RNA binding
protein. The CsrA homologs are found in most bacterial species, in the
pseudomonads they are called repressor of secondary metabolites (RsmA and RsmE).[2] The CsrA proteins generally bind to the
Shine-Dalgarno sequence of
messenger RNAs and either inhibit translation or facilitate mRNA decay.[3]
A consensus secondary structure and primary sequence for the targets of the CsrA RNA binding protein.
The CsrA protein binds to a
Stem-loop RNA motif. The ability of the protein to inhibit translation of bound mRNAs can be countered by the expression of sRNAs such as
CsrB,
CsrC,
RsmZ,
RsmY and
RsmX that contain multiple copies of the RNA motif. These RNAs sequester CsrA, which allows the translation of the previously inhibited bound mRNAs. A study investigating specific binding of CsrA in the Salmonella transcriptome has identified 467 binding sites.[6]