… an ‘expression platform’ for gene regulation.

9. A metabolite-binding ‘aptamer’ domain and … … an ‘expression platform’ for gene regulation. Riboswitch Functions • Direct (protein-free) binding of metabolite to RNA • Metabolite-dependent regulation of genes These two activities are accomplished by two functionally separate domains on the RNA: X 1 2 3 4 U U U U U Courtesy: Ron Breaker Lab (Yale University)

10. X 5´ ORF A U G X GUACGG AG ORF A U G 5´ X ORF A A A A A A U G 5´ Riboswitch Mechanisms They also affect RNA integrity, and perhaps splicing and stability. Ligand binding leads to mRNA cleavage by a new natural ribozyme. X Ligand binding could control splicing in eukayotes. Possibly, ligand binding to the 3´ untranslated region could affect mRNA stability. Courtesy: Ron Breaker Lab (Yale University)

11. Riboswitch Ligands There are 8 confirmed riboswitches with unique metabolite ligands. Many more conserved RNA motifs are currently under investigation. Courtesy: Ron Breaker Lab (Yale University)

12. Courtesy: Ron Breaker Lab (Yale University)

15. Manufacturing of Affy GeneChip

16. Affymetrix E. coli GeneChip Image