preQ1 class I type I riboswitch (IMAGE) University of Rochester Medical Center Caption Ribbon diagram of a preQ1 class I type I riboswitch determined by x-ray crystallography. This small, folded RNA senses two stacked metabolites (shaded in green) to control gene regulation and is representative of the most common group of preQ1 riboswitches in the biosphere. The preQ1 riboswitch is used by several human pathogens, such as Neisseria gonorrhoeae depicted in the background. Credit The image was created by Griffin Schroeder and Joseph Wedekind; the bacterial illustration was drawn by Alissa Eckert, the CDC Public Health Image Library Usage Restrictions None License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.