AI Article Synopsis
- Glutamine synthetase (GS) is crucial for nitrogen assimilation when nitrogen is limited, but the regulation of related metabolic pathways remains unclear.
- The expression of SucA, a component of 2-oxoglutarate dehydrogenase, is repressed under nitrogen scarcity through post-transcriptional mechanisms involving the Hfq-dependent sRNA GlnZ, which binds to the GS mRNA.
- This study highlights the complex interaction between mRNA, GlnZ, and transcriptional regulators like Nac to maintain balance in metabolite supply and demand during nitrogen metabolism.
Article Abstract
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 and . The repression is exerted at the post-transcriptional level by an Hfq-dependent sRNA GlnZ generated from the 3'UTR of the GS-encoding mRNA. Enterobacterial GlnZ variants contain a conserved seed sequence and primarily regulate through base-pairing far upstream of the translation initiation region. During growth on glutamine as the nitrogen source, the 3'UTR deletion mutants expressed SucA at higher levels than the and wild-type strains, respectively. In , the transcriptional regulator Nac also participates in the repression of . Lastly, this study clarifies that the release of GlnZ from the mRNA by RNase E is essential for the post-transcriptional regulation of . Thus, the mRNA coordinates the two independent functions to balance the supply and demand of the fundamental metabolites.
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| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9731577 | PMC |
| http://dx.doi.org/10.7554/eLife.82411 | DOI Listing |
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