EC Number   |
General Information |
Reference |
|---|
   2.7.7.59 | malfunction |
the higher the UTP concentration, the longer GlnK remains uridylylated with the wild-type enzyme, while there is enough UTP, GlnDDELTAACT catalyzes the uridylylation/deuridylylation futile cycle, confirming the regulatory role of the ACT domain |
-, 760630 |
| 2.7.7.59 | metabolism |
Azospirillum brasilense is a diazotrophic microorganism capable of associating with roots of important grasses and cereals, promoting plant growth and increasing crop yields. Nitrogen levels and the Ntr regulatory system control the nitrogen metabolism in Azospirillum brasilense. This system comprises the nitrogen regulatory proteins GlnD, which is capable of adding uridylyl groups to the PII proteins, GlnB (PII-1) and GlnZ (PII-2), under limiting nitrogen levels. Under such conditions, the histidine kinase NtrB (nitrogen regulatory protein B) cannot interact with GlnB and phosphorylate NtrC (nitrogen regulatory protein C). The phosphorylated form of NtrC acts as a transcriptional activator of genes involved in the metabolism of alternative nitrogen sources. Analysis of proteomic profile and proteins regulated by nitrogen availability in Azospirillum brasilense ntrC, identification of proteins likely to belong to the NtrC regulon, overview |
-, 761746 |
| 2.7.7.59 | metabolism |
the PII proteins play an important role in this system by modulating the cellular metabolism through physical interaction with protein partners. Herbaspirillum seropedicae, a nitrogen-fixing bacterium, has two PII proteins paralogues, GlnB and GlnK. The interaction of Herbaspirillum seropedicae PII proteins with its targets is regulated by allosteric ligands and by reversible post-translational uridylylation. The interaction between PII proteins and its targets is regulated at two distinct levels: the allosteric binding of molecular effectors and the post-translational modification status. By controlling the post-translational state of PII proteins, the GlnD enzyme acts as a primary sensor of nitrogen in the cell. Regulatory role of the ACT domain |
-, 760630 |
| 2.7.7.59 | metabolism |
to adapt to environments with variable nitrogen sources and richness, the widely distributed homotrimeric PII signalling proteins bind their allosteric effectors ADP/ATP/2-oxoglutarate, and experience nitrogen-sensitive uridylylation of their flexible T-loops at Tyr51 by enzyme GlnD, regulating their interactions with effector proteins |
760999 |
| 2.7.7.59 | more |
crystal structure determination and analysis at 1.9 A resolution of the purified Escherichia coli GlnB (EcGlnB) PII protein in fully uridylylated form (EcGlnB-UMP3), structure-function analysis, overview. The T-loop is not visible. Unlike crystalline non-uridylylated EcGlnB, in which T-loops are fixed, uridylylation renders the T-loop highly mobile because of loss of contacts mediated by Tyr51, with concomitant abolition of T-loop anchoring via Arg38 on the ATP site. Analysis of mechanisms of PII selectivity for ATP and of PII-UMP3 signalling, proposing a model for the architecture of the complex of EcGlnBUMP3 with the uridylylation-sensitive PII target ATase (which adenylylates/deadenylylates glutamine synthetase [GS]) and with GS. Good X-ray diffracting crystals of trigonal shape and good size are obtained with fully uridylylated EcGlnB only when ATP, MgCl2 and 2-oxolutarate are present |
760999 |
| 2.7.7.59 | physiological function |
control for PII interaction with target proteins involves the covalent modification of the T-loop, such as uridylylation, phosphorylation or adenylylation. The uridylylation of PII proteins occurs in a conserved residue of tyrosine (Tyr51) in the T-loop. Uridylylation of Tyr51 renders a T-loop more mobile in comparison with the unmodified protein. The PII uridylylation is catalyzed by the GlnD enzyme, which also catalyzes the removal of the uridylyl group from PII. The choice between uridylyl transferase (UTase) and the uridylyl-removing activities (UR) of GlnD is essential to the function of the Ntr system and is supposedly dependent on the in vivo fluctuation of key metabolites. The deuridylylation activity of Herbaspirillum seropedicae GlnD protein is regulated by the glutamine:2-oxoglutarate ratio. GlnD can sense the glutamine:2-oxoglutarate ratio. The ACT domains of GlnD are the protein sensor of environment clues of nitrogen availability. Regulatory role of the ACT domain |
-, 760630 |
| 2.7.7.59 | physiological function |
the uridylyltransferase/uridylyl-cleavage enzyme GlnD has a role in free-living growth and in symbiotic nitrogen exchange that does not depend on its substrates, the PII proteins. An in-frame deletion mutationglnDsm2 mutation has severe defects in regulating free-living and symbiotic nitrogen metabolismcompared to the glnBglnK double-deletion strain lacking the substrates of GlnD. Data indicate that the GlnD uridylyltransferase is required for proper regulation of nitrogen exchange in symbiosis with the host plant but that the PII substrate proteins are not involved in this regulation or that the glnD-sm2 mutation disrupts some additional activity of GlnD |
723230 |
