1nnl
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Crystal structure of Human Phosphoserine Phosphatase
OverviewOverview
The crystal structure of human phosphoserine phosphatase (HPSP) in the, open conformation has been determined at a resolution of 1.53 A. The, crystals are orthorhombic, belonging to space group C222(1), with, unit-cell parameters a = 49.03, b = 130.25, c = 157.29 A. The asymmetric, unit contains two molecules. Phase information was derived from a, multiwavelength anomalous dispersion (MAD) experiment conducted at three, wavelengths using a selenomethionine-derivative crystal of HPSP. The, structure was refined using CNS to a final crystallographic R value of, 21.6% (R(free) = 23.4%). HPSP is a dimeric enzyme responsible for the, third and final step of the l-serine biosynthesis pathway. It catalyses, the Mg2+-dependent hydrolysis of l-phosphoserine. Recently, the structure, of HPSP in complex with an inhibitor bound to the active site has been, reported to be the open conformation of the enzyme. Here, the structure of, HPSP is reported in the absence of substrate in the active site. Evidence, is presented that HPSP in an uncomplexed form is in an even more open, conformation than in the inhibitor complex. In this state, the enzyme is, partially unfolded to allow the substrate to enter the active site., Binding of the substrate causes HPSP to shift to the closed conformation, by stabilizing the partially unfolded region. In the present structure a, Ca2+ ion is bound to the active site and an explanation is given why HPSP, is not active when in the active site Mg2+ is replaced by a Ca2+ ion.
About this StructureAbout this Structure
1NNL is a Single protein structure of sequence from Homo sapiens with CL and CA as ligands. Active as Phosphoserine phosphatase, with EC number 3.1.3.3 Full crystallographic information is available from OCA.
ReferenceReference
High-resolution structure of human phosphoserine phosphatase in open conformation., Peeraer Y, Rabijns A, Verboven C, Collet JF, Van Schaftingen E, De Ranter C, Acta Crystallogr D Biol Crystallogr. 2003 Jun;59(Pt 6):971-7. Epub 2003, May 23. PMID:12777757
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