Impact of adenylyltransferase GlnE on nitrogen starvation response in Corynebacterium glutamicum

Adenylyltransferases regulate glutamine synthetase activity in enterobacteria and actinomycetes such as Streptomyces coelicolor, Mycobacterium tuberculosis and Corynebacterium glutamicum. In this study the effects of a mutation of the glnE gene, coding for adenylyltransferase, on transcriptome and metabolome profiles of C. glutamicum was investigated. As expected, the glnE deletion led to a loss of activity regulation of glutamine synthetase. Astonishingly, additionally the glnE mutation caused a nitrogen limitation response on the transcript level as well. Interestingly, induction of the nitrogen starvation response in the mutant strain was unusually weak and GlnK was present in adenylylated form even without nitrogen starvation. The results obtained might hint to a moonlighting function of adenylyltransferase and might be explained by protein interaction of adenylyltransferase and an unknown interaction partner of the nitrogen regulatory network.