1mne
TRUNCATED HEAD OF MYOSIN FROM DICTYOSTELIUM DISCOIDEUM COMPLEXED WITH MG-PYROPHOSPHATE
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OverviewOverview
The structure of the magnesium pyrophosphate complex of the truncated head, of Dictyostelium myosin has been determined by molecular replacement at, 2.7 A resolution and refined to a crystallographic R-factor of 16.0%. The, crystals belong to the orthorhombic space group P2(1)2(1)2, where a =, 105.2 A, b = 182.1 A, and c = 54.5 A. The conformation of the protein, around the magnesium pyrophosphate is very similar to that seen when, magnesium ADP-beryllium fluoride binds in the active site. The latter, complex mimics the binding of ATP prior to hydrolysis. The pyrophosphate, molecule occupies the beta- and gamma-phosphate sites, where the two, phosphorus atoms are in the same positions as the beta-phosphate and the, BeFx moiety of the beryllium fluoride-trapped ADP. The surrounding active, site residues are almost perfectly superimposable in the two structures, and the hydrogen-bonding interactions that the PPi makes with the protein, are essentially identical. The similarity between the MgPPi and MgADP.BeFx, complex with S1Dc suggests that the conformational change, which occurs, when ATP binds to actomyosin and which reduces the affinity of myosin for, actin, is caused by the binding of the gamma- and beta-phosphate groups of, the nucleotide. This then implies that the role of the remainder of the, substrate is to increase the binding affinity for myosin and thus to drive, the equilibrium toward dissociation of myosin from actin.
About this StructureAbout this Structure
1MNE is a Single protein structure of sequence from Dictyostelium discoideum with MG and POP as ligands. Active as Myosin ATPase, with EC number 3.6.4.1 Full crystallographic information is available from OCA.
ReferenceReference
X-ray structure of the magnesium(II)-pyrophosphate complex of the truncated head of Dictyostelium discoideum myosin to 2.7 A resolution., Smith CA, Rayment I, Biochemistry. 1995 Jul 18;34(28):8973-81. PMID:7619796
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