Disease relevance of ECs0450

• Topology of the PhoR protein of Escherichia coli and functional analysis of internal deletion mutants [1].
• The periplasmic domain of EnvZ was also replaced with the non-homologous periplasmic domain of the histidine kinase PhoR of Bacillus subtilis [2].

High impact information on ECs0450

• PhoR protein is a histidine protein kinase, induced in Pi starvation and is a transmembrane protein [3].
• The two-component regulatory pair PhoR/PhoB is responsible for upregulation of Pho regulon expression in response to P(i)-limiting environments [4].
• Phosphorylated PhoR showed stability under basic conditions but not acidic conditions, indicating that the phosphorylation probably occurs on a conserved histidine residue [5].
• We constructed a plasmid with a mutant phoR gene (phoR1084), which encoded a PhoR protein (PhoR1084) lacking the amino-terminal hydrophobic region of the intact protein [6].
• Therefore, the sequences of the PhoB and PhoR proteins have considerable homologies with those of the OmpR and EnvZ proteins, respectively, indicating that the two operons share a common ancestor [7].

Biological context of ECs0450

• These results suggest that the maximal level of the operon is induced as consequences of both the increase in the quantity of the PhoR protein and of functional change of the protein as a positive regulator, which are induced by phosphate limitation [8].
• The amino acid sequence of the PhoR protein has significant homology with that of the EnvZ protein, which is a regulator for the omp regulon [7].
• The catalytic domain of PhoR is sufficient for the low-phosphate inducible expression of Pho regulon genes since removing the N-terminal membrane-associated domain did not alter the kinetics of Pho induction, albeit the total level of induction was decreased (1) [9].
• PhoP and PhoR are members of the two-component signal transduction system believed to regulate gene expression in response to limiting phosphate [10].
• Although PhoR1084 that lacked the hydrophobic amino-terminal region of the native PhoR protein transphosphorylated PhoB, it could not phosphorylate PhoM-open reading frame 2 [11].

Anatomical context of ECs0450

• The results suggest that PhoR protein is anchored to the cytoplasmic membrane by the amino-terminal region [12].
• Western blot analysis of the subcellular fractions obtained by differential centrifugation indicated that the intact PhoR and PhoR1084 proteins are located in the inner membrane and cytoplasmic fractions, respectively [12].

Associations of ECs0450 with chemical compounds

• These results indicate that the energy levels of the phosphoryl groups on PhoP and PhoR are very similar [9].
• While the autokinase reaction, the forward phosphotransfer reaction from PhoR approximately P to PhoP, and the release of inorganic phosphate from PhoP approximately P in the presence of PhoR require Mg(2+), the reverse phosphotransfer from PhoP approximately P to PhoR does not [9].
• Here we examined the effects of uncoupling PhoB synthesis and PhoR synthesis from their normal controls by placing each under the tight control of the arabinose-regulated P(araB) promoter or the rhamnose-regulated P(rhaB) promoter [13].

References