Dual-function sRNA encoded peptide SR1P modulates moonlighting activity of <i>B. subtilis</i> GapA

<p>SR1 is a dual-function sRNA from <i>B. subtilis</i> that acts as a base-pairing regulatory RNA and as a peptide-encoding mRNA. Both functions of SR1 are highly conserved. Previously, we uncovered that the SR1 encoded peptide SR1P binds the glycolytic enzyme GapA resulting in stabilization of <i>gapA</i> mRNA. Here, we demonstrate that GapA interacts with RNases Y and J1, and this interaction was RNA-independent. About 1% of GapA molecules purified from <i>B. subtilis</i> carry RNase J1 and about 2% RNase Y. In contrast to the GapA/RNase Y interaction, the GapA/RNaseJ1 interaction was stronger in the presence of SR1P. GapA/SR1P-J1/Y displayed <i>in vitro</i> RNase activity on known RNase J1 substrates. Moreover, the RNase J1 substrate SR5 has altered half-lives in a Δ<i>gapA</i> strain and a Δ<i>sr1</i> strain, suggesting <i>in vivo</i> functions of the GapA/SR1P/J1 interaction. Our results demonstrate that the metabolic enzyme GapA moonlights in recruiting RNases while GapA bound SR1P promotes binding of RNase J1 and enhances its activity.</p