@article{mbs:/content/journal/micro/10.1099/00221287-98-2-369, author = "Newman, B.Mary and Cole, J.A.", title = "Lack of a Regulatory Function for Glutamine Synthetase Protein in the Synthesis of Glutamate Dehydrogenase and Nitrite Reductase in Escherichia coli K12", journal= "Microbiology", year = "1977", volume = "98", number = "2", pages = "369-377", doi = "https://doi.org/10.1099/00221287-98-2-369", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-98-2-369", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", abstract = "SUMMARY: Synthesis of glutamine synthetase (GS) in anaerobic batch cultures of Escherichia coli was repressed when excess NH4 + was available, but derepressed during growth with a poor nitrogen source. In wild-type bacteria there was only a weak inverse correlation between the activities of GS and glutamate dehydrogenase (GDH) during growth in various media. No positive correlations were found between the activities of GS and nitrite reductase, or between GS and cytochrome C 552: both of these proteins were synthesized normally by mutants that contained no active GS. Although activities of GS and GDH were low in two mutants that are unable to synthesize cytochrome C 552 or reduce nitrite because of defects in the nir A gene, the nir A defect was separated from the GS and GDH defects by transduction with bacteriophage PI. Attempts to show that catabolite repression of proline oxidase synthesis could be relieved during NH4+ starvation also failed. It is, therefore, unlikely that nitrite reduction or proline oxidation by E. coli are under positive control by GS protein. The regulation of the synthesis of enzymes for the utilization of secondary nitrogen sources in E. coli is, therefore, different from that in Klebsiella aerogenes, but is similar to that in Salmonella typhimurium. ", }