1g5b
BACTERIOPHAGE LAMBDA SER/THR PROTEIN PHOSPHATASE
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OverviewOverview
The protein phosphatase encoded by bacteriophage lambda (lambda PP), belongs to a family of Ser/Thr phosphatases (Ser/Thr PPases) that includes, the eukaryotic protein phosphatases 1 (PP1), 2A (PP2A), and 2B, (calcineurin). These Ser/Thr PPases and the related purple acid, phosphatases (PAPs) contain a conserved phosphoesterase sequence motif, that binds a dinuclear metal center. The mechanisms of phosphoester, hydrolysis by these enzymes are beginning to be unraveled. To utilize, lambda PP more effectively as a model for probing the catalytic mechanism, of the Ser/Thr PPases, we have determined its crystal structure to 2.15 A, resolution. The overall fold resembles that of PP1 and calcineurin, including a conserved beta alpha beta alpha beta structure that comprises, the phosphoesterase motif. Substrates and inhibitors probably bind in a, narrow surface groove that houses the active site dinuclear Mn(II) center., The arrangement of metal ligands is similar to that in PP1, calcineurin, and PAP, and a bound sulfate ion is present in two novel coordination, modes. In two of the three molecules in the crystallographic asymmetric, unit, sulfate is coordinated to Mn2 in a monodentate, terminal fashion, and the two Mn(II) ions are bridged by a solvent molecule. Two additional, solvent molecules are coordinated to Mn1. In the third molecule, the, sulfate ion is triply coordinated to the metal center with one oxygen, coordinated to both Mn(II) ions, one oxygen coordinated to Mn1, and one, oxygen coordinated to Mn2. The sulfate in this coordination mode displaces, the bridging ligand and one of the terminal solvent ligands. In both, sulfate coordination modes, the sulfate ion is stabilized by hydrogen, bonding interactions with conserved arginine residues, Arg 53 and Arg 162., The two different active site structures provide models for intermediates, in phosphoester hydrolysis and suggest specific mechanistic roles for, conserved residues.
About this StructureAbout this Structure
1G5B is a Single protein structure of sequence from Enterobacteria phage lambda with MN, HG and SO4 as ligands. Full crystallographic information is available from OCA.
ReferenceReference
Structure of the bacteriophage lambda Ser/Thr protein phosphatase with sulfate ion bound in two coordination modes., Voegtli WC, White DJ, Reiter NJ, Rusnak F, Rosenzweig AC, Biochemistry. 2000 Dec 19;39(50):15365-74. PMID:11112522
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