Role of glnB and glnD gene products in regulation of the glnALG operon of Escherichia coli

Abstract

We have isolated insertion and deletion mutants in glnB, the structural gene of PI,, a member of the adenylylation system for glutamine synthetase of Escherichia coli, to study the role of PI, in the regulation of the synthesis of glutamine synithetase and of histidase in response to nitrogen deprivation or excess. We have studied the effects of this mutation alone and combined with nul mutations resulting from the insertion of transposons or from a deletion in the other genes affecting this regulation, ginD, glnF (ntrA), ginG (ntrC), and glnL (ntrB). Our rqsults confirm that only the products of glnF and ginG are essential for this regulation. In cells of the wild type, the response is mediated by the products of ginD and glnB via the product of glnL, In the condition of nitrogen excess, PII, the product of glnB, appears to convert the product of glnL to a form that prevents the activation of transcription of the structural gekes for glutamine synthetase and for histidase by the products of glnF and ginG. During nitrogen deprivation, uridylyltransferase, the product of ginD, is activated

Phosphoprotein PII from Cyanobacteria

“…To analyze glnA expression in these transformants, the glutamine synthetase activity was determined, which is proportional to the amount of gZnA gene product. The vector controls exhibited similar glutamine synthetase activities to those reported previously for the non-transformed strains ( Table 2 ; Bueno et al, 1985). Compared with the parental strain YMC10, the glnB mutant RB9060 exhibited elevated glutamine synthetase levels in the nitrogen-excess medium.…”

“…For cloning experiments, ligations were transformed in competent E. coli DH5a cells, which were grown in Luria-Bertani medium (Sambrook et al, 1989). For the physiological analysis of E. coli cells expressing the Synechococcus gEnB gene, cells were grown either under nitrogen excess (Luria-Bertani medium containing 0.2% glutamine and 0.4% glucose) or in nitrogen-limiting minimal medium containing either 0.2 % glutamine and 0.4 % glucose or 0.2% arginine and 0.4 % glucose as described by Bueno et al (1985).…”

A common switch in activation of the response regulators NtrC and PhoB: phosphorylation induces dimerization of the receiver modules.

“…F13202 carries a transposon insertion in ntrC and a deletion of glnB, the structural gene for the PII protein. PIT is a negative regulator of NtrC-P, together with the histidine kinase NtrB, it stimulates the dephosphorylation of NtrC-P under conditions of nitrogen excess (Bueno et al, 1985;Ninfa and Magasanik, 1986;Keener and Kustu, 1988;Atkinson et al, 1994). F13202 lacks glnB, resulting in the constitutive phosphorylation of the introduced NtrC hybrid proteins.…”

“…A virulent derivative of phage P1 was used for all transductions. Strains were grown in LB medium (Miller, 1972), GLBgln, GNgln (Bueno et al, 1985), PNgln (Feng et al, 1992) or MOPS minimal medium supplemented with 10 mM K2HPO4 for phosphate excess or 0.1 mM K2HPO4 for phosphate limitation conditions (Neidhardt et al, 1974), as indicated in the figure legends. All media contained 10 ,ug/ml kanamycin, 5 ,ug/ml tetracycline or 100 gg/ml ampicillin when appropriate.…”

Common patterns – unique features: nitrogen metabolism and regulation in Gram-positive bacteria

“…From the P II protein, the signal is transferred to ATase, which regulates GS activity. Two P II -type proteins are present in E. coli: the products of glnB (Bueno et al, 1985;van Heeswijk et al, 2009) and glnK (van Heeswijk et al, 1995(van Heeswijk et al, , 1996. P II and GlnK form heterotrimers that are proposed to be important for fine tuning the nitrogen regulatory cascade (van Heeswijk et al, 2000).…”