Disease relevance of URE2

• In fact, ure2 hypersensitivity to Cd(II) remains the same, even when glutathione is used as sole source of nitrogen for cell growth [1].
• The expression of the yeast Ure2 protein and its two N- and C-terminal HA-(YPYPVDYA) epitope and His-tag fusions has been enhanced in E. coli by selected silent mutagenesis of the URE2 gene [2].
• These findings suggest the involvement of PHGPX genes and a novel role of URE2 in Al toxicity/resistance in S. cerevisiae [3].
• In vitro, Ure2p and Sup35p form amyloid, a filamentous protein structure, high in beta-sheet with a characteristic green birefringent staining by the dye Congo Red. Amyloid deposits are a cardinal feature of Alzheimer's disease, non-insulin-dependent diabetes mellitus, the transmissible spongiform encephalopathies, and many other diseases [4].
• The [URE3] nonchromosomal genetic element is an infectious form (prion) of the Ure2 protein, apparently a self-propagating amyloidosis [5].

High impact information on URE2

• Furthermore, an unbiased functional screen for [PIN(+)] prions uncovered the known prion gene, URE2, the proposed prion gene, NEW1, and nine novel candidate prion genes all carrying prion domains [6].
• Here, we show that the presence of prions formed by Rnq1 or Ure2 is sufficient to make cells [PIN(+)] [6].
• Here we demonstrate a potentially general and scalable method of identifying such molecules by application to a particular protein, Ure2p, which represses the transcription factors Gln3p and Nil1p [7].
• One compound, which we call uretupamine, specifically activates a glucose-sensitive transcriptional pathway downstream of Ure2p [7].
• By probing a high-density microarray of small molecules generated by diversity-oriented synthesis with fluorescently labelled Ure2p, we performed 3,780 protein-binding assays in parallel and identified several compounds that bind Ure2p [7].

Biological context of URE2

• URE2 repression appears to be limited to nitrogen assimilatory systems and does not affect genes involved in carbon, inositol, or phosphate metabolism or in mating-type control and sporulation [8].
• These studies further characterize the roles that URE2 and PMA1 play in regulating intracellular ion homeostasis [9].
• A second protein encoded by URE2 possesses the genetic characteristics of a negative regulator of nitrogen catabolic gene expression [10].
• 2) [PSI] propagation requires SUP35 and [URE3] propagation requires URE2 with recessive chromosomal mutants having the same phenotypes as the presence of the respective dominant non-Mendelian element [11].
• Biochemical data measuring Ure2p phosphorylation coupled with the partition analysis indicate that there are distinct signaling branches downstream of the Tor proteins [12].

Anatomical context of URE2

• The regulation of expression from the URE2 internal ribosome entry site appears to be through the levels of eIF2A protein, which has been found to be inherently unstable with a half-life of approximately 17 min [13].
• Differential resistance to proteinase K digestion of the yeast prion-like (Ure2p) protein synthesized in vitro in wheat germ extract and rabbit reticulocyte lysate cell-free translation systems [14].
• The Ure2p yeast prion-like protein was translated in vitro in the presence of labeled [35S]methionine in either rabbit reticulocyte lysate (RRL) or wheat germ extract (WGE) cell-free systems [14].

Associations of URE2 with chemical compounds

• The predicted URE2 gene product has homology to glutathione S-transferases [15].
• Active URE2 gene product was required for the inactivation of glutamine synthetase upon addition of glutamine to cells growing with glutamate as the source of nitrogen [15].
• The participation of nitrogen repression and the regulators GLN3 and URE2 in the proline utilization pathway was evaluated in this study [8].
• We propose that the URE2-GLN3 system regulates enzyme synthesis, in response to glutamine and glutamate, to adjust the intracellular concentration of ammonia so as to maintain glutamine at the level required for optimal growth [16].
• In contrast, deletion of URE2 greatly enhances a cell's ability to withstand toxic concentrations of Zn(II) and Mo(VI) [1].
• The kinetics of the glutaredoxin activity of Ure2 showed positive cooperativity for the substrate glutathione in both the soluble native state and in amyloid-like fibrils, indicating native-like dimeric structure within Ure2 fibrils [17].

Physical interactions of URE2

• Ure2p binds to Gln3p and Gat1p and is required for NCR-sensitive transcription to be repressed and for nuclear exclusion of these transcription factors [18].

Enzymatic interactions of URE2

• When carbon and nitrogen are abundant, the phosphorylated Ure2p anchors the also phosphorylated Gln3p and Nil1p in the cytoplasm [19].

Regulatory relationships of URE2

• Enhanced green fluorescent protein-Gat1p is nuclear when Gat1p-dependent transcription is high and cytoplasmic when it is inhibited by overproduction of Ure2p [20].
• In this report it is shown that the formation of this enzyme is dependent upon the functional GLN3 gene and that the response to nitrogen availability is under the control of the URE2 gene product [21].
• Moreover, overexpression of Ure2p suppresses the ability of Mks1p overexpression to allow ureidosuccinate uptake on ammonia [22].

Other interactions of URE2

• Rapamycin, a Tor protein inhibitor, like growth with a poor nitrogen source, promotes nuclear localization of Gln3p and Gat1p. gln3 Delta and ure2 Delta mutants are partially resistant and hypersensitive to growth inhibition by rapamycin, respectively [23].
• Ure2p, which is not a GATA family member, inhibits Gln3p/Gat1p from functioning in the presence of good nitrogen sources [20].
• The inactivity of Ure2p, caused by either a ure2 mutation or the presence of the [URE3] prion, increases DAL5 transcription and thus enables Saccharomyces cerevisiae to take up ureidosuccinate (USA+) [24].
• Mutations in URE2 suppress the sensitivity of calcineurin mutants to Na+, Li+, and Mn2+, and increase their survival during treatment with mating pheromone. ure2 mutations require both the transcription factor Gln3p and the Na+ ATPase Pmr2p to confer Na+ and Li+ tolerance [9].
• We also had observed that the activity levels of the also periplasmic invertase, coded by SUC2, were 6-fold lower in ure2 mutant cells in comparison to wild-type cells collected at stationary phase [19].

Analytical, diagnostic and therapeutic context of URE2

• Here we show by electron microscopy that [URE3] cells overexpressing Ure2p contain distinctive, filamentous networks in their cytoplasm, and demonstrate by immunolabeling that these networks contain Ure2p [25].
• We compare the time course of structural changes monitored by thioflavin T (ThT) binding fluorescence and atomic force microscopy for Ure2 and a series of prion domain mutants under a range of conditions [26].
• Protease digestions of Ure2p filaments and soluble Ure2p are comparable when analyzed by Coomassie staining as by Western blot [27].
• A combination of size exclusion chromatography, sedimentation velocity, and electron microscopy demonstrates that the soluble form of Ure2p consists at least of three forms of the protein as follows: a monomeric, dimeric, and tetrameric form whose abundance is concentration-dependent [28].
• By the use of limited proteolysis, intrinsic fluorescence, and circular dichroism measurements, we bring strong evidence for the existence of at least two structural domains in Ure2p molecules [28].

References