title: Identification of the high affinity Mn2+ binding site of bacteriophage lambda phosphoprotein phosphatase: effects of metal ligand mutations on electron paramagnetic resonance spectra and phosphatase activities.
abstract: Bacteriophage lambda phosphoprotein phosphatase (lambdaPP) has structural similarity to the mammalian Ser/Thr phosphoprotein phosphatases (PPPs) including the immunosuppressant drug target calcineurin. PPPs possess a conserved active site containing a dinuclear metal cluster, with metal ligands provided by a phosphoesterase motif plus two additional histidine residues at the C-terminus. Multiple sequence alignment of lambdaPP with 28 eubacterial and archeal phosphoesterases identified active site residues from the phosphoesterase motif and in many cases 2 additional C-terminal His metal ligands. Most highly similar to lambdaPP are E. coli PrpA and PrpB. Using the crystal structure of lambdaPP [Voegtli, W. C., et al. (2000) Biochemistry 39, 15365-15374] as a structural and active site model for PPPs and related bacterial phosphoesterases, we have studied mutant forms of lambdaPP reconstituted with Mn(2+) by electron paramagnetic resonance (EPR) spectroscopy, Mn(2+) binding analysis, and phosphatase kinetics. Analysis of Mn(2+)-bound active site mutant lambdaPP proteins shows that H22N, N75H, and H186N mutations decrease phosphatase activity but still allow mononuclear Mn(2+) and [(Mn(2+))(2)] binding. The high affinity Mn(2+) binding site is shown to consist of M2 site ligands H186 and Asn75, but not H22 from the M1 site which is ascribed as the lower affinity site.
authors.affiliation: Section of Hematology Research and Department of Biochemistry and Molecular Biology, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: White
authors.forename: N J
authors.initials: NJ
authors.lastname: Reiter
authors.forename: R A
authors.initials: RA
authors.lastname: Sikkink
authors.forename: L
authors.initials: L
authors.lastname: Yu
authors.forename: F
authors.initials: F
authors.lastname: Rusnak
mesh_terms: D000595:Amino Acid Sequence; D001216:Asparagine / Q000235:genetics / Q000378:metabolism; D010582:Bacteriophage lambda / Q000201:enzymology* / Q000235:genetics; D001665:Binding Sites / Q000235:genetics; D017124:Conserved Sequence; D004578:Electron Spin Resonance Spectroscopy; D004789:Enzyme Activation / Q000235:genetics; D006639:Histidine / Q000235:genetics / Q000378:metabolism; D008024:Ligands; D008345:Manganese / Q000378:metabolism*; D008667:Metalloproteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D020539:Sequence Analysis, Protein; D017386:Sequence Homology, Amino Acid; D017186:Titrimetry
chemical_list: D008024:Ligands; D008667:Metalloproteins; D008345:Manganese; D006639:Histidine; D001216:Asparagine; D010749:Phosphoprotein Phosphatases