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Nick Reiter
Last active: 1/21/2015

Mn2+ is a native metal ion activator for bacteriophage lambda protein phosphatase.

Reiter TA, Reiter NJ, Rusnak F
Biochemistry. 2002 41 (51): 15404-9

PMID: 12484780 · DOI:10.1021/bi026317o

Bacteriophage lambda protein phosphatase (lambdaPP) is a member of a large family of metal-containing phosphoesterases, including purple acid phosphatase, protein serine/threonine phosphatases, 5'-nucleotidase, and DNA repair enzymes such as Mre11. lambdaPP can be activated several-fold by various divalent metal ions, with Mn(2+) and Ni(2+) providing the most significant activation. Despite the extensive characterization of purified lambdaPP in vitro, little is known about the identity and stoichiometry of metal ions used by lambdaPP in vivo. In this report, we describe the use of metal analysis, activity measurements, and whole cell EPR spectroscopy to investigate in vivo metal binding and activation of lambdaPP. Escherichia coli cells overexpressing lambdaPP show a 22.5-fold increase in intracellular Mn concentration and less dramatic changes in the intracellular concentration of other biologically relevant metal ions compared to control cells that do not express lambdaPP. Phosphatase activity assessed using para-nitrophenylphosphate as substrate is increased 850-fold in cells overexpressing lambdaPP, indicating the presence of metal-activated enzyme in cell lysate. EPR spectra of intact cells overexpressing lambdaPP exhibit resonances previously attributed to mononuclear Mn(2+) and dinuclear [(Mn(2+))(2)] species bound to lambdaPP. Spin quantitation of EPR spectra of intact E. coli cells overexpressing lambdaPP indicates the presence of approximately 40 microM mononuclear Mn(2+)-lambdaPP and 60 microM [(Mn(2+))(2)]-lambdaPP. The data suggest that overexpression of lambdaPP results in a mixture of apo-, mononuclear-Mn(2+), and dinuclear-[(Mn(2+))(2)] metalloisoforms and that Mn(2+) is a physiologically relevant activating metal ion in E. coli.

MeSH Terms (10)

Bacteriophage lambda Binding Sites Cations, Divalent Electron Spin Resonance Spectroscopy Enzyme Activation Escherichia coli Manganese Metals Protein Tyrosine Phosphatases Receptor-Like Protein Tyrosine Phosphatases, Class 2

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