Abstract
AbstractUsing a cDNA cloning and sequencing approach we have shown that Francisella tularensis expresses homologues of several small RNAs(sRNAs) that are well-conserved among diverse bacteria. We have also discovered two abundant putative sRNAs that share no sequence similarity or conserved genomic context with any previously annotated regulatory transcripts. Deletion of either of these two loci led to significant changes in the expression of several mRNAs that likely include the cognate target(s) of these sRNAs. Deletion of these sRNAs did not, however, significantly alter F. tularensis growth under various stress conditions in vitro, its replication in murine cells, or its ability to induce disease in a mouse model of F. tularensis infection.
Highlights
Two classes of bacterial antisense RNAs can be distinguished: – cis-encoded RNAs are located on the strand opposite the target gene, perfectly complementary to their targets over a long sequence stretch, – trans-encoded RNAs are located in another chromosomal location, with short and only partial complementarity to their target RNAs
We have identified two novel small RNAs, the first in F. tularensis
It is important to recall that most small non-protein-coding RNAs (sRNAs) affect gene expression negatively
Summary
Antisense RNAs, ranging in length from 50 to 500 nucleotides, regulate the physiological and virulent functions of bacteria in response to environmental changes and host signals. These small non-protein-coding RNAs (sRNAs) act by basepairing usually modulating the translation (Fig. 1a) and stability (Fig. 1b) of mRNAs
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