RNAIII is a small RNA which is known to regulate the expression of many Staphylococcus aureus

Staphylococcus aureus

Staphylococcus aureus is a facultative anaerobic Gram-positive coccal bacterium. It is frequently found as part of the normal skin flora on the skin and nasal passages. It is estimated that 20% of the human population are long-term carriers of S. aureus. S. aureus is the most common species of...

genes encoding exoproteins and cell wall associated proteins. In S. aureus, RNAIII acts as the effector of the agr quorum sensing

Quorum sensing

Quorum sensing is a system of stimulus and response correlated to population density. Many species of bacteria use quorum sensing to coordinate gene expression according to the density of their local population. In similar fashion, some social insects use quorum sensing to determine where to nest...

 system and is transcribed from the P3 operon. The RNAIII transcript also contains the 26 amino acid delta-haemolysin gene (hld). RNAIII regulates the expression of the transcription factor rot by blocking its translation. It has been suggested that RNAIII binds to the rot mRNA in an antisense fashion occluding the Shine-Dalgarno sequence

Shine-Dalgarno sequence

The Shine-Dalgarno sequence , proposed by Australian scientists John Shine and Lynn Dalgarno , is a ribosomal binding site in the mRNA, generally located 8 basepairs upstream of the start codon AUG. The Shine-Dalgarno sequence exists only in prokaryotes. The six-base consensus sequence is AGGAGG;...

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