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. 2022 Nov 28;11:e82411. doi: 10.7554/eLife.82411

Figure 7. GlnA and GlnZ expressed from glnA mRNA facilitate nitrogen assimilation independently.

Figure 7.

The expression of GlnA and GlnZ is induced by the two-component system NtrBC upon nitrogen limitation. The glutamine synthetase (GS)-glutamine 2-oxoglutarate amidotransferase (GOGAT) (GlnA-GlnBD) pathway assimilates ammonia using 2-oxoglutarate (2-OG) as the carbon skeleton. GlnZ sRNA is released from the 3′UTR of glnA mRNA by RNase E to repress the expression of SucA at the post-transcriptional level. In Escherichia coli, the transcriptional regulator nitrogen assimilation control (Nac), whose expression is activated by NtrC, represses the transcription of sucABCD operon in parallel. The repression of 2-oxoglutarate dehydrogenase (OGDH) (SucAB) upon nitrogen limitation results in the accumulation of 2-OG and redirects the carbon flow from the TCA cycle to the GS-GOGAT pathway.