title: Bacterial RNA thermometers: molecular zippers and switches.
abstract: Bacteria use complex strategies to coordinate temperature-dependent gene expression. Many genes encoding heat shock proteins and virulence factors are regulated by temperature-sensing RNA sequences, known as RNA thermometers (RNATs), in their mRNAs. For these genes, the 5' untranslated region of the mRNA folds into a structure that blocks ribosome access at low temperatures. Increasing the temperature gradually shifts the equilibrium between the closed and open conformations towards the open structure in a zipper-like manner, thereby increasing the efficiency of translation initiation. Here, we review the known molecular principles of RNAT action and the hierarchical RNAT cascade in Escherichia coli. We also discuss RNA-based thermosensors located upstream of cold shock and other genes, translation of which preferentially occurs at low temperatures and which thus operate through a different, more switch-like mechanism. Finally, we consider the potential biotechnological applications of natural and synthetic RNATs.
authors.affiliation: Lehrstuhl für Biologie der Mikroorganismen, Ruhr-Universität Bochum, Universittsstrasse 150, NDEF 06/783, 44780                 Bochum, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Kortmann
authors.forename: Franz
authors.initials: F
authors.lastname: Narberhaus
mesh_terms: D001419:Bacteria / Q000235:genetics* / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006360:Heat-Shock Proteins / Q000096:biosynthesis / Q000235:genetics; D009690:Nucleic Acid Conformation; D014176:Protein Biosynthesis; D059370:RNA Folding; D012329:RNA, Bacterial / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D013696:Temperature; D037521:Virulence Factors / Q000096:biosynthesis / Q000235:genetics
chemical_list: D006360:Heat-Shock Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D037521:Virulence Factors