FourU: a novel type of RNA thermometer in Salmonella.
The translation of many heat shock and virulence genes is controlled by RNA thermometers. Usually, they are located in the 5'-untranslated region (5'-UTR) and block the Shine-Dalgarno (SD) sequence by base pairing. Destabilization of the structure at elevated temperature permits ribosome binding and translation initiation. We have identified a new type of RNA thermometer in the 5'-UTR of the Salmonella agsA gene, which codes for a small heat shock protein. Transcription of the agsA gene is controlled by the alternative sigma factor sigma(32). Additional translational control depends on a stretch of four uridines that pair with the SD sequence. Mutations in this region affect translation in vivo. Structure probing experiments demonstrate a temperature-controlled opening of the SD region in vitro. Toeprinting (primer extension inhibition) shows that ribosome binding is dependent on high temperatures. Together with a postulated RNA thermometer upstream of the Yersinia pestis virulence gene lcrF (virF), the 5'-UTR of Salmonella agsA might be the founding member of a new class of RNA thermometers that we propose to name 'fourU' thermometers.
Waldminghaus
Torsten
T
Lehrstuhl für Biologie der Mikroorganismen, Ruhr-Universität Bochum, 44780 Bochum, Germany.
Heidrich
Nadja
N
Brantl
Sabine
S
Narberhaus
Franz
F
D020121:5' Untranslated Regions / Q000737:chemistry / Q000378:metabolism; D001483:Base Sequence; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D014176:Protein Biosynthesis / Q000235:genetics*; D012329:RNA, Bacterial / Q000737:chemistry* / Q000378:metabolism; D012333:RNA, Messenger / Q000737:chemistry* / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism; D012486:Salmonella typhimurium / Q000235:genetics* / Q000378:metabolism; D013696:Temperature
D020121:5' Untranslated Regions; D012329:RNA, Bacterial; D012333:RNA, Messenger