Abstract 1320 Discovery and Validation of ROSE-like RNA Thermometers in the 5'-UTRs of ABC Transporter Genes

ATP-binding cassette (ABC) transporters are a large family of cellular transporters found across prokaryotes and eukaryotes, which use the hydrolysis of ATP to transport a large variety of substrates across the cell membrane. In bacteria, ABC transporters can play an important role in virulence and pathogenicity. In this study, we aimed to elucidate the molecular mechanism for the upregulation of ABC transporters under heat stress. RNA thermometers are noncoding RNA structural elements in the 5' untranslated region (UTR) of genes. In most cases, they result in the upregulation of downstream genes in response to changes in temperature within a physiological range. The ROSE-like class of RNA thermometers is characterized by a specific motif in which U(U/C)GCU nucleotides are predicted to imperfectly base pair with the Shine-Dalgarno (SD) in a stem with a bulged G nucleotide. We utilized a bioinformatic structural search to discover ROSE-like RNA thermometers based on their characteristic motif. Manual curation of the search results led to our discovery of a multitude of predicted ROSE-like RNA thermometers in the 5'-UTRs of diverse ABC transporter genes in different bacteria, suggesting a potential widespread means of temperature-dependent regulation of these genes. Using β-galactosidase assays, we validated five predicted ROSE-like RNA thermometers upstream of different ABC transporter genes. Additional characterization of mutants revealed the dependence of thermoregulatory activity on the ROSE-like motif. Our study suggests that ROSE-like RNA thermometers may play a critical role in the upregulation of ABC transporters under heat stress. This work was supported in part by California Lutheran University (CLU) start-up funding (M.M.A.), the intramural program of the National Heart, Lung and Blood Institute, National Institutes of Health (L.F.M.P.), the John Stauffer Charitable TrustFoundation - CLU (A.Y.T.), & the Swenson Science Summer Research Fellowship - CLU (E.L.T).