CeBiTec Colloquium: 2009/01/26 Prof. Dr. Franz Narberhaus, Lehrstuhl für Biologie der Mikroorganismen, Ruhr-Universität Bochum

2009/01/26, 17:15

CeBiTec Laboratory Building, Room G2-104

cis- and trans-acting regulatory RNAs in bacteria

Abstract:

cis-acting regulatory RNAs control bacterial gene expression by the formation of complex structures in the 5’-untranslated region (5’-UTR) of mRNAs. Riboswitches and RNA thermometers belong to this class. RNA thermometers are thermo-responsive structures in the 5’-UTR of certain heat shock and virulence gene transcripts. In most cases, the ribosome-binding site is trapped by base pairing at low temperatures. Melting of the structure at increasing temperature permits ribosome access and translation initiation.
We study different classes of RNA thermometers. ROSE (Repression Of heat Shock gene Expression) elements control translation of small heat shock genes in many alpha- and gamma-proteobacteria. The NMR structure of the temperature-responsive region of a typical ROSE element revealed the molecular basis for temperature sensing. FourU-type RNA thermometers are characterized by a stretch of four uridines that pair with the SD sequence at low temperatures. Recent studies include potential fourU thermometers upstream of virulence genes in Yersinia and Vibrio species. A novel class of RNA thermometers in cyanobacteria will also be presented.
trans-acting regulatory RNAs usually are small non-coding RNAs (sRNAs) endoced in intergenic regions. They control gene expression by base pairing with their partially complementary mRNA targets. We are in the process of uncovering the complete sRNA inventory of the plant pathogen Agrobacterium tumefaciens using bioinformatic and deep sequencing technology. Selected candidates, in particular virulence-induced sRNAs are under investigation.