title: Increased ribozyme activity in crowded solutions.
abstract: Noncoding RNAs must function in the crowded environment of the cell. Previous small-angle x-ray scattering experiments showed that molecular crowders stabilize the structure of the Azoarcus group I ribozyme, allowing the ribozyme to fold at low physiological Mg(2+) concentrations. Here, we used an RNA cleavage assay to show that the PEG and Ficoll crowder molecules increased the biochemical activity of the ribozyme, whereas sucrose did not. Crowding lowered the Mg(2+) threshold at which activity was detected and increased total RNA cleavage at high Mg(2+) concentrations sufficient to fold the RNA in crowded or dilute solution. After correcting for solution viscosity, the observed reaction rate was proportional to the fraction of active ribozyme. We conclude that molecular crowders stabilize the native ribozyme and favor the active structure relative to compact inactive folding intermediates.
authors: From the T. C. Jenkins Department of Biophysics, The Johns Hopkins University, Baltimore, Maryland 21218.
authors: Ravi
authors: R
authors: Desai
authors: Duncan
authors: D
authors: Kilburn
authors: Hui-Ting
authors: HT
authors: Lee
authors: Sarah A
authors: SA
authors: Woodson
mesh_terms: D020627:Azoarcus / Q000235:genetics* / Q000378:metabolism; D015636:Magnesium Chloride / Q000378:metabolism; D008956:Models, Chemical; D008970:Molecular Weight; D009690:Nucleic Acid Conformation; D017510:Protein Folding; D016337:RNA, Catalytic / Q000737:chemistry* / Q000378:metabolism*; D012996:Solutions / Q000378:metabolism*; D014783:Viscosity
chemical_list: D016337:RNA, Catalytic; D012996:Solutions; D015636:Magnesium Chloride
keywords: Macromolecular Crowding; PEG; RNA Catalysis; RNA Folding; Ribozyme; X-ray Scattering