4bx0
Crystal Structure of a Monomeric Variant of murine Chronophin (Pyridoxal Phosphate phosphatase)
Structural highlights
FunctionPLPP_MOUSE Protein serine phosphatase that dephosphorylates 'Ser-3' in cofilin and probably also dephosphorylates phospho-serine residues in DSTN. Regulates cofilin-dependent actin cytoskeleton reorganization. Required for normal progress through mitosis and normal cytokinesis. Does not dephosphorylate phospho-threonines in LIMK1. Does not dephosphorylate peptides containing phospho-tyrosine. Pyridoxal phosphate phosphatase. Has some activity towards pyridoxal 5'-phosphate (PLP), pyridoxine 5'-phosphate (PMP) and pyridoxine 5'-phosphate (PNP), with a highest activity with PLP followed by PNP (By similarity). Publication Abstract from PubMedMammalian phosphatases of the haloacid dehalogenase (HAD) superfamily have emerged as important regulators of physiology and disease. Many of these enzymes are stable homodimers, yet the role of their dimerization is largely unknown. Here, we explore the function of the obligatory homodimerization of chronophin, a mammalian HAD phosphatase known to dephosphorylate pyridoxal 5'-phosphatase (PLP) and serine/threonine-phosphorylated proteins. The exchange of two residues in the murine chronophin homodimerization interface (chronophinAla194Lys, Ala195Lys; chronophinKK) yields a constitutive monomer, both in vitro and in cells. The catalytic activity of monomeric chronophin towards PLP is strongly impaired. X-ray crystallographic studies of chronophinKK reveal that dimer formation is essential for an intermolecular arginine-arginine-tryptophan stacking interaction that positions a critical histidine residue in the substrate specificity loop of chronophin for PLP coordination. Analysis of all available crystal structures of HAD hydrolases that are grouped together with chronophin in the C2a-type structural subfamily uncovers a highly conserved mode of dimerization that results in intermolecular contacts involving the substrate specificity loop. Our results explain how the dimerization of HAD hydrolases contributes to their catalytic efficiency and substrate specificity. Chronophin dimerization is required for proper positioning of its substrate specificity loop.,Kestler C, Knobloch G, Tessmer I, Jeanclos E, Schindelin H, Gohla A J Biol Chem. 2013 Dec 14. PMID:24338687[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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