The GlnE enzyme, functioning as an adenylyltransferase/adenylyl-removing enzyme, plays a crucial role in reversible adenylylation of glutamine synthetase (GS), which in turn regulates bacterial nitrogen assimilation. Genomic analysis of Azorhizobium caulinodans ORS571 revealed an open reading frame encoding a GlnE protein, whose function in the free-living and symbiotic states remains to be elucidated. A glnE deletion mutant retained high GS activity even under nitrogen-rich conditions. However, a reduction in growth was observed for the mutant strain at lower NH