RNase III-Binding-mRNAs Revealed Novel Complementary Transcripts in Streptomyces

Abstract

<i>cis</i>-Antisense RNAs (asRNAs) provide very simple and effective gene expression control due to the perfect complementarity between regulated and regulatory transcripts. In <i>Streptomyces</i>, the antibiotic-producing clade, the antisense control system is not yet understood, although it might direct the organism's complex development. Initial studies in <i>Streptomyces</i> have found a number of asRNAs. Apart from this, hundreds of mRNAs have been shown to bind RNase III, the double strand-specific endoribonuclease. In this study, we tested 17 mRNAs that have been previously co-precipitated with RNase III for antisense expression. Our RACE mapping showed that all of these mRNAs possess cognate asRNA. Additional tests for antisense expression uncovered <i>as-adpA, as-rnc, as3983, as-sigB, as-sigH</i>, and <i>as-sigR</i> RNAs. Northern blots detected the expression profiles of 18 novel transcripts. Noteworthy, we also found that only a minority of asRNAs respond to the absence of RNase III enzyme by increasing their cellular levels. Our findings suggest that antisense expression is widespread in <i>Streptomyces</i>, including genes of such important developmental regulators, as AdpA, RNase III, and sigma factors.