scholarly journals Effect of mutations in Escherichia coli glnL (ntrB), encoding nitrogen regulator II (NRII or NtrB), on the phosphatase activity involved in bacterial nitrogen regulation.

1994 ◽  
Vol 269 (45) ◽  
pp. 28294-28299
Author(s):  
E S Kamberov ◽  
M R Atkinson ◽  
P Chandran ◽  
A J Ninfa
Keyword(s):  
Escherichia Coli ◽  
Phosphatase Activity ◽  
Nitrogen Regulation

scholarly journals Effects of zinc and other metal ions on the stability and activity of Escherichia coli alkaline phosphatase

1971 ◽  
Vol 124 (1) ◽  
pp. 25-30 ◽  
Author(s):  
C. N. A. Trotman ◽  
C. Greenwood
Keyword(s):  
Escherichia Coli ◽  
Alkaline Phosphatase ◽  
Metal Ions ◽  
Phosphatase Activity ◽  
Structural Stability ◽  
Zinc Content ◽  
Sedimentation Velocity ◽  
Reducing Agent ◽  
Deficient Mutant ◽  
The Stability

Measurement of the ultraviolet circular dichroism of apo-(alkaline phosphatase) in urea solutions showed substantial denaturation in 3m-urea. A zinc-deficient mutant alkaline phosphatase behaved similarly. The stability of the enzyme in 6m-urea was followed as a function of its zinc content and was found to be dependent on the first two of the four zinc atoms bound by apoenzyme. Phosphatase activity was mostly dependent on a second pair of zinc atoms. Mn2+, Co2+, Cu2+ or Cd2+ also restored structural stability. Sedimentation-velocity and -equilibrium experiments revealed that dissociation of the dimer accompanied apoenzyme denaturation in urea concentrations of 1m or higher, without treatment with disulphide-reducing agent.

scholarly journals Genetic and Biochemical Analysis of Phosphatase Activity of Escherichia coli NRII (NtrB) and Its Regulation by the PII Signal Transduction Protein

2003 ◽  
Vol 185 (4) ◽  
pp. 1299-1315 ◽  
Author(s):  
Augen A. Pioszak ◽  
Alexander J. Ninfa
Keyword(s):  
Escherichia Coli ◽  
Signal Transduction ◽  
Binding Site ◽  
Phosphatase Activity ◽  
Atp Binding ◽  
Wild Type ◽  
Small Surface ◽  
Central Domain ◽  
Atp Binding Site ◽  
Terminal Domain

ABSTRACT Mutant forms of Escherichia coli NRII (NtrB) were isolated that retained wild-type NRII kinase activity but were defective in the PII-activated phosphatase activity of NRII. Mutant strains were selected as mimicking the phenotype of a strain (strain BK) that lacks both of the related PII and GlnK signal transduction proteins and thus has no mechanism for activation of the NRII phosphatase activity. The selection and screening procedure resulted in the isolation of numerous mutants that phenotypically resembled strain BK to various extents. Mutations mapped to the glnL (ntrB) gene encoding NRII and were obtained in all three domains of NRII. Two distinct regions of the C-terminal, ATP-binding domain were identified by clusters of mutations. One cluster, including the Y302N mutation, altered a lid that sits over the ATP-binding site of NRII. The other cluster, including the S227R mutation, defined a small surface on the “back” or opposite side of this domain. The S227R and Y302N proteins were purified, along with the A129T (NRII2302) protein, which has reduced phosphatase activity due to a mutation in the central domain of NRII, and the L16R protein, which has a mutation in the N-terminal domain of NRII. The S227R, Y302N, and L16R proteins were specifically defective in the PII-activated phosphatase activity of NRII. Wild-type NRII, Y302N, A129T, and L16R proteins bound to PII, while the S227R protein was defective in binding PII. This suggests that the PII-binding site maps to the “back” of the C-terminal domain and that mutation of the ATP-lid, central domain, and N-terminal domain altered functions necessary for the phosphatase activity after PII binding.

scholarly journals Characterization of the Catalytic Activities of the PhoQ Histidine Protein Kinase of Salmonella entericaSerovar Typhimurium

2001 ◽  
Vol 183 (5) ◽  
pp. 1787-1791 ◽  
Author(s):  
Martin Montagne ◽  
Alexandre Martel ◽  
Hervé Le Moual
Keyword(s):  
Escherichia Coli ◽  
Phosphatase Activity ◽  
Divalent Cations ◽  
Histidine Protein Kinase ◽  
Catalytic Activities ◽  
Serovar Typhimurium ◽  
High Concentrations ◽  
Kinetics Of ◽  
Autokinase Activity

ABSTRACT Studies of Escherichia coli membranes that were highly enriched in the Salmonella enterica serovar Typhimurium PhoQ protein showed that the presence of ATP and divalent cations such as Mg2+, Mn2+, Ca2+, or Ba2+ resulted in PhoQ autophosphorylation. However, when Mg2+ or Mn2+was present at concentrations higher than 0.1 mM, the kinetics of PhoQ autophosphorylation were strongly biphasic, with a rapid autophosphorylation phase followed by a slower dephosphorylation phase. A fusion protein lacking the sensory and transmembrane domains retained the autokinase activity but could not be dephosphosphorylated when Mg2+ or Mn2+ was present at high concentrations. The instability of purified [32P]phospho-PhoP in the presence of PhoQ-containing membranes indicated that PhoQ also possesses a phosphatase activity. The PhoQ phosphatase activity was stimulated by increasing the Mg2+ concentration. These data are consistent with a model in which Mg2+ binding to the sensory domain of PhoQ coordinately regulates autokinase and phosphatase activities.

scholarly journals Acid Phosphatase Activity in Freshwater Ecosystems of Western Cuba and its Relationship with Water Quality

2021 ◽  
Author(s):  
Jeny Adina Larrea Murrell ◽  
Beatriz Romeu Alvarez ◽  
Daysi Lugo Moya ◽  
Marcia M. Rojas Badía
Keyword(s):  
Escherichia Coli ◽  
Acid Phosphatase ◽  
Phosphatase Activity ◽  
Acid Phosphatase Activity ◽  
Oxygen Demand ◽  
N:P Ratio ◽  
Freshwater Ecosystems ◽  
San Juan ◽  
San Juan River ◽  
The Impact

Abstract Enzyme activity plays an important role in the functioning of aquatic ecosystems. It is sensitive to changes in environmental conditions such as pH, temperature, and nutrient concentration. The objective of this work was to determine the acid phosphatase activity (AcPA) in the Almendares and San Juan rivers (western Cuba) and its relationship with physicochemical and microbiological indicators. For this purpose, AcPA, temperature, pH, total dissolved solids, electrical conductivity, dissolved oxygen, concentration of nitrates, nitrites, ammonium, phosphates, total heterotrophs, enterococci, Escherichia coli, thermotolerant coliforms, chlorophyll a and chemical oxygen demand (COD) were determined at three sampling stations on the Almendares River and at three sampling stations on the San Juan River. In addition, the nutrient pollution index (NPI) and the N:P ratio were calculated. In both ecosystems, spatio-temporal variability was observed in the enzymatic activity. In the Almendares River (polluted ecosystem), AcPA was positively correlated with nitrate concentration and COD. While in the San Juan River (slightly contaminated ecosystem) the AcPA correlated negatively with the pH and NPI and positively with the concentrations of total heterotrophs, Escherichia coli, chlorophyll a and the N:P ratio. These results show the impact of anthropogenic pollution on AcPA in freshwater ecosystems with a tropical climate.

scholarly journals Role of His243 in the phosphatase activity of EnvZ in Escherichia coli.

1997 ◽  
Vol 179 (4) ◽  
pp. 1413-1416 ◽  
Author(s):  
K Skarphol ◽  
J Waukau ◽  
S A Forst
Keyword(s):  
Escherichia Coli ◽  
Phosphatase Activity

scholarly journals An Escherichia coli protein that exhibits phosphohistidine phosphatase activity towards the HPt domain of the ArcB sensor involved in the multistep His-Asp phosphorelay

1998 ◽  
Vol 27 (3) ◽  
pp. 573-585 ◽  
Author(s):  
Tomoaki Ogino ◽  
Masahiro Matsubara ◽  
Naoki Kato ◽  
Yoshihiro Nakamura ◽  
Takeshi Mizuno
Keyword(s):  
Escherichia Coli ◽  
Phosphatase Activity

scholarly journals Genetic and Biochemical Studies of Phosphatase Activity of PhoR

2003 ◽  
Vol 185 (3) ◽  
pp. 1112-1115 ◽  
Author(s):  
Daniel O. Carmany ◽  
Kristine Hollingsworth ◽  
William R. McCleary
Keyword(s):  
Escherichia Coli ◽  
Phosphatase Activity ◽  
Histidine Kinase ◽  
Deletion Mutants ◽  
Biochemical Activity ◽  
Biochemical Studies ◽  
Histidine Phosphorylation ◽  
Phosphorylation Domain ◽  
Phosphate Regulon

ABSTRACT In Escherichia coli, PhoR is the histidine kinase of the phosphate regulon. It has been postulated that PhoR may function as a phospho-PhoB phosphatase. Experiments with four precise phoR deletion mutants supported this hypothesis and suggested that this activity resides within the histidine phosphorylation domain. This biochemical activity was confirmed by using a separately expressed histidine phosphorylation domain.

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