Regulatory RNAs in Bacteria

Abstract

RNA regulators in bacteria are a heterogenous group of molecules that act by various mechanisms to modulate a wide range of physiological responses. One class comprises riboswitches, which are parts of the mRNAs they regulate. These leader sequences fold into structures amenable to conformational changes upon the binding of small molecules. Riboswitches thus sense and respond to the availability of various nutrients in the cell. Other small transcripts bind to proteins, among them global regulators, and antagonize their functions. The largest and most extensively studied set of small RNA regulators act through base pairing with RNAs, usually modulating the translation and stability of mRNAs. The majority of these small RNAs regulate responses to changes in environmental conditions. Finally, a recently discovered group of RNA regulators, known as the CRISPR RNAs, contain short regions of homology to bacteriophage and plasmid sequences. CRISPR RNAs interfere with bacteriophage infection and plasmid conjugation by targeting the homologous foreign DNA through an unknown mechanism. Here we discuss what is known about these RNA regulators, as well as the many intriguing questions that remain to be addressed.

Esre: A novel essential non‐coding RNA in Escherichia coli

“…They usual regulate the expression of target genes by binding to their targets via complementary sequence [13]. Only few sRNAs are essential for the cells, but each of them has distinct mechanism of function.…”

Folding of the SAM-I riboswitch

“…A tale with a twist Sébastien H. Eschbach, 1 Patrick St-Pierre, 1 riboswitches, which are genetic modulators located in untranslated regions of mRNAs. [3][4][5][6][7] Riboswitches are composed of two modular domains: an aptamer and an expression platform.…”

The impact of CRISPR repeat sequence on structures of a Cas6 protein–RNA complex

“…The clustered regularly interspaced short palindromic repeats (CRISPRs) are found in many bacteria and archaea genomes and are recently demonstrated to confer small RNA-based adaptive immunity against invasive genetic elements. [1][2][3][4][5][6][7][8] CRISPR loci typically consist of several to hundreds of short ($30-40-nucleotide) repeats separated by short ($30-40-nucleotide) variable sequences (spacers) and are associated with one or more heterogenous families of cas genes that encode Cas proteins. 9,10 The spacer sequences are short DNA segments derived from past infection and they establish the specificity for obstruction of future invasion.…”