A theophylline responsive riboswitch based on helix slipping controls gene expression in vivo.
Riboswitches are newly discovered regulatory elements which control a wide set of basic metabolic pathways. They consist solely of RNA, sense their ligand in a preformed binding pocket and perform a conformational switch in response to ligand binding resulting in altered gene expression. We have utilized the enormous potential of RNA for molecular sensing and conformational changes to develop novel molecular switches with predetermined structural transitions in response to the binding of a small molecule. To validate these in vivo, we exploit the distance-dependent inhibitory potential of secondary structure elements placed close to the bacterial ribosome binding site. We created a translational control element by combining the theophylline aptamer with a helical communication module for which a ligand-dependent one-nucleotide slipping mechanism had been proposed. This structural element was inserted at a position just interfering with translation in the non ligand-bound form. Addition of the ligand then shifts the inhibitory element to a distance which permits efficient translation. We present here a novel regulatory mechanism in the first rationally designed, in vivo active RNA switch. Its use of a slippage mechanism to control gene expression makes it different from natural riboswitches which are based on sequestration or antitermination.
Suess
Beatrix
B
Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstrasse 5, 91058 Erlangen, Germany. bsuess@biologie.uni-erlangen.de
Fink
Barbara
B
Berens
Christian
C
Stentz
Régis
R
Hillen
Wolfgang
W
D001483:Base Sequence; D005786:Gene Expression Regulation; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D014176:Protein Biosynthesis; D012313:RNA / Q000737:chemistry; D038621:Regulatory Sequences, Ribonucleic Acid; D013806:Theophylline / Q000494:pharmacology*
D038621:Regulatory Sequences, Ribonucleic Acid; D012313:RNA; D013806:Theophylline