TY - JOUR TI - Glutamine synthetase mRNA releases sRNA from its 3′UTR to regulate carbon/nitrogen metabolic balance in Enterobacteriaceae AU - Miyakoshi, Masatoshi AU - Morita, Teppei AU - Kobayashi, Asaki AU - Berger, Anna AU - Takahashi, Hiroki AU - Gotoh, Yasuhiro AU - Hayashi, Tetsuya AU - Tanaka, Kan A2 - Westermann, Alexander J A2 - Rath, Satyajit A2 - Westermann, Alexander J A2 - Klaehn, Stephan VL - 11 PY - 2022 DA - 2022/11/28 SP - e82411 C1 - eLife 2022;11:e82411 DO - 10.7554/eLife.82411 UR - https://doi.org/10.7554/eLife.82411 AB - Glutamine synthetase (GS) is the key enzyme of nitrogen assimilation induced under nitrogen limiting conditions. The carbon skeleton of glutamate and glutamine, 2-oxoglutarate, is supplied from the TCA cycle, but how this metabolic flow is controlled in response to nitrogen availability remains unknown. We show that the expression of the E1o component of 2-oxoglutarate dehydrogenase, SucA, is repressed under nitrogen limitation in Salmonella enterica and Escherichia coli. The repression is exerted at the post-transcriptional level by an Hfq-dependent sRNA GlnZ generated from the 3′UTR of the GS-encoding glnA mRNA. Enterobacterial GlnZ variants contain a conserved seed sequence and primarily regulate sucA through base-pairing far upstream of the translation initiation region. During growth on glutamine as the nitrogen source, the glnA 3′UTR deletion mutants expressed SucA at higher levels than the S. enterica and E. coli wild-type strains, respectively. In E. coli, the transcriptional regulator Nac also participates in the repression of sucA. Lastly, this study clarifies that the release of GlnZ from the glnA mRNA by RNase E is essential for the post-transcriptional regulation of sucA. Thus, the mRNA coordinates the two independent functions to balance the supply and demand of the fundamental metabolites. KW - nitrogen assimilation KW - TCA cycle KW - small RNA KW - 3′UTR KW - RNase E JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -