BIOLOGICZNA ROLA sRNA

12 06 2025

Zapraszamy na seminarium instytutowe: w poniedziałek 16 czerwca o godz. 14 w sali 102B mgr Julia Konarska z Zakładu Mikrobiologii Molekularnej wygłosi seminarium pt. „Biologiczna rola sRNA OmrA i jego wpływ na poziom wirulencji i zdolności adaptacyjnych enteropatogenu Yersinia enterocolitica”.

Abstract:

Yersinia enterocolitica exhibits a dual lifestyle, thriving both as a non-pathogenic saprophyte and as a gastrointestinal enteropathogen. Rapid responses to changing environmental conditions are achieved partly by small regulatory RNAs (sRNAs), which play a vital role in orchestrating regulatory networks and stress responses that govern bacterial survival and behavior. Among these sRNAs, OmrA stands out for its role in post-transcriptional regulation by interacting with specific mRNAs, influencing their stability and translation. This study aimed to investigate the significance of OmrA in physiology and behavior in response to fluctuating environmental conditions in two Y. enterocolitica strains with varying degrees of virulence (bioserotype 2/O:9 versus 1B/O:8), as well as to identify OmrA targets and determine their involvement in pathophysiology.

To determine the biological relevance of OmrA, RT-qPCR analysis was conducted on selected candidate transcripts in Y. enterocolitica. Several mRNAs encoding proteins involved in virulence and physiology were quantified in the ΔomrA mutant compared to the omrA-overexpression strain. It was confirmed that the sRNA OmrA regulates virulence-associated genes in Y. enterocolitica. RT-qPCR analysis showed that OmrA inhibits invA, pgaA, efeU, and efeO expression at 26°C. Fluorescence measurements of subsequently constructed translational fusions with gfp-gene further confirmed reduced pgaABCD and invA expression under OmrA overexpression, while efeUOB remained unaffected.

In parallel, physiological tests were conducted on Y. enterocolitica strains with different levels of OmrA activity. Biofilm formation was assessed through crystal violet staining and revealed a dual role for OmrA: it either significantly inhibited or promoted biofilm formation depending on the strain. Motility was evaluated using a semi-liquid agar assay, showing that both overexpression and deletion of omrA impaired bacterial movement. Hemagglutination activity was determined using a sheep blood assay and was observed exclusively in the highly virulent strain with OmrA overexpression. Despite this, the ΔomrA mutant retained virulence in the Galleria mellonella killing assay, indicating a complex role for OmrA in virulence regulation. Siderophore production, assessed via the Chrome Azurol Sulfonate (CAS) assay, was increased upon OmrA overexpression in strain 1B/O:8, confirming OmrA’s involvement in iron acquisition. Stress resistance tests showed that OmrA-deficient strains had improved survival under osmotic and acidic stress conditions, whereas OmrA overexpression enhanced resistance to oxidative stress.

In conclusion, OmrA plays a pivotal role in regulating key physiological processes such as biofilm formation, motility, virulence, stress adaptation, and post-transcriptional gene expression. These findings highlight the significance of OmrA in the environmental adaptability and pathogenic potential of Y. enterocolitica and support its potential as a target for therapeutic strategies aimed at modulating bacterial behavior and survival.