Poster abstracts
Poster number 111 submitted by Martin OSteen
A Regulatory RNA:RNA interaction in Listeria monocytogenes
Martin OSteen (University of Michigan Department of Biophysics ), Aldrex Munsayac (University of Michigan Department of Chemistry), Jocelyn Chen (University of Michigan Department of Chemistry ), Sarah C. Keane (University of Michigan Department of Biophysics, University of Michigan Department of Chemistry)
Abstract:
Non-coding RNA elements found in the 5′ and 3′ untranslated regions (UTRs) of some
messenger RNA transcripts can alter gene expression in the absence of regulatory proteins.
These elements are tuned to respond to environmental changes, such as temperature (RNA
thermosensors) and metabolite concentration (riboswitches). Regulation by these elements is predominantly cis-acting, functioning on the downstream gene, and can occur at both the transcriptional and translational levels. Trans-regulation by these elements is rare, with few examples described in the literature. One such example is found in Listeria monocytogenes. L. monocytogenes is a Gram-positive bacterium commonly found in soil and decaying vegetation as a saprophyte. Upon ingestion, L. monocytogenes undergoes a virulence gene program to facilitate infection and intracellular spread, causing listeriosis. This transition is controlled by a transcriptional activator, positive regulatory factor A (PrfA). In turn, PrfA translation is regulated by an RNA thermosensor located in the 5′ UTR of the prfA transcript, which is tuned to allow translation at temperatures above 34 °C. Additional suppression of prfA translation is mediated by a series of S-adenosyl methionine (SAM)-sensitive riboswitches (sreA and sreB), demonstrating a complex regulatory network to prevent inadvertent PrfA expression. However, the sequence, molecular, and environmental determinants underlying this interaction are not well understood. Herein, we describe our efforts to characterize and elucidate the sequence and environmental determinants required for the sreA:prfA interaction. Our findings demonstrate that this interaction is sensitive to temperature and influenced by the chemical environment. Mutagenesis of the sreA riboswitch in functional translational assays and electromobility shift assays (EMSAs) revealed critical sequence determinants for both binding and translational inhibition of prfA.
Keywords: RNA Regulation, RNARNA Interactions, Riboswitch