Poster abstracts
Poster number 6 submitted by Raeven Bastock
Identification of temperature responsive post-transcriptional regulatory sRNAs in Staphylococcus aureus
Raeven A. Bastock (Biological Sciences at Ohio University ), Rebecca A. Keogh (Biological Sciences at Ohio University ), Ronan K. Carroll (Biological Sciences at Ohio University ), Erin R. Murphy (Biological Sciences at Ohio University )
Abstract:
Staphylococcus aureus is a Gram-positive opportunistic pathogen that colonizes the anterior nares of approximately 30% of the global population. Colonization is most commonly asymptomatic however, it is associated with a higher risk of invasive infections. If the bacterium internalizes, it can cause potentially fatal infections. In the transition between the nares and the body, the bacterium is subject to many environmental changes, including a slight temperature difference. The average temperature of the nares is 34C while the internal body is 37C. Temperature responsive post-transcriptional RNA regulatory elements, such as RNA thermometers, are known to exist in many Gram-negative bacteria but, few examples have been described in Gram-positive pathogens to date. Given all of this previous knowledge, we investigated the influence of temperature on S. aureus gene expression. RNAseq and proteomic analyses were performed on cultures grown at three different temperatures: 34C, the temperature of the nares, 37C, internal body temperature, and 40C, representative of pyrexia. Cross-reference analysis of the data sets revealed extremely low correlation between transcript and protein levels and was highly suggestive of post-transcriptional regulation. RNAseq analysis revealed that sRNAs were the most altered transcripts with 29 in total altered between 34C V 37C and 18 altered between 37C V 40C. Interestingly higher sRNA expression values were mostly observed at the lower temperature. Fifteen sRNAs had a significant change in both paired analyses (34C V 37C and 37C V 40C) in a thermo-responsive manner. The discrepancy between transcript and protein levels is highly suggestive of post-transcriptional regulation, and we hypothesize that these 15 temperature-responsive sRNAs play a critical role in the transition of the pathogen from the nares to systemic infection. One temperature-responsive sRNA of particular interest is Teg49. Located in the 5’ UTR of sarA, Teg49 is processed into a trans-acting sRNA that has been shown to influence virulence factor expression, independent of SarA activity. We are investigating these temperature-responsive sRNAs to determine if they play a role as S. aureus, transitions from a colonizing commensal, to an invasive pathogen.
Keywords: S aureus, temperature