Abstract
Bacterial small non-coding RNAs (sRNAs) are gene expression modulators respond to environmental changes, stressful conditions, and pathogenesis. In this study, by using a combined bioinformatic and experimental approach, eight novel sRNA genes were identified in intracellular pathogen Brucella melitensis. BSR0602, one sRNA that was highly induced in stationary phase, was further examined and found to modulate the intracellular survival of B. melitensis. BSR0602 was present at very high levels in vitro under stresses similar to those encountered during infection in host macrophages. Furthermore, BSR0602 was found to be highly expressed in the spleens of infected mice, suggesting its potential role in the control of pathogenesis. BSR0602 targets the mRNAs coding for gntR, a global transcriptional regulator, which is required for B. melitensis virulence. Overexpression of BSR0602 results in distinct reduction in the gntR mRNA level. B. melitensis with high level of BSR0602 is defective in bacteria intracellular survival in macrophages and defective in growth in the spleens of infected mice. Therefore, BSR0602 may directly inhibit the expression of gntR, which then impairs Brucellae intracellular survival and contributes to Brucella infection. Our findings suggest that BSR0602 is responsible for bacterial adaptation to stress conditions and thus modulate B. melitensis intracellular survival.
Highlights
The survival of pathogens within a host is highly dependent upon their ability to sense and adapt to changes in the host environments
While there has been a rapid increase in identification of bacterial small noncoding RNAs (sRNAs) over the last few years, the identification of mRNA targets and the study of sRNAs function have proceeded more slowly (Arnvig and Young, 2009)
We identified eight novel sRNAs and systematically analyzed one of them, BSR0602, which modulates the virulence capacities of B. melitensis
Summary
The survival of pathogens within a host is highly dependent upon their ability to sense and adapt to changes in the host environments This entails a coordinated regulation of virulence genes in response to various environmental stresses. Trans-encoded sRNAs is the best characterized and most extensively studied sRNAs, which could regulate gene expression by imperfect base-pairing with target mRNAs, thereby modulating mRNA translation and/or stability (Gottesman, 2004; Livny and Waldor, 2007; Papenfort and Vogel, 2010). This family of sRNAs is generally located in the “intergenic region” between proteincoding sequences. In Gram negative bacteria, the RNA binding protein Hfq is usually required to facilitate the interaction between trans-encoded sRNAs and their target mRNAs (Arnvig and Young, 2012)
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