1MNE

TRUNCATED HEAD OF MYOSIN FROM DICTYOSTELIUM DISCOIDEUM COMPLEXED WITH MG-PYROPHOSPHATE

Summary for 1MNE

• Entry DOI: 10.2210/pdb1mne/pdb
• Descriptor: MYOSIN, MAGNESIUM ION, PYROPHOSPHATE 2-, ... (4 entities in total)
• Functional Keywords: atpase, myosin, coiled coil, actin-binding, atp-binding, heptad repeat pattern, methylation, alkylation, phosphorylation, contractile protein
• Biological source: Dictyostelium discoideum
• Cellular location: Cytoplasm, cell cortex: P08799
• Total number of polymer chains: 1
• Total formula weight: 86949.27

Authors

Smith, C.A.,Rayment, I. (deposition date: 1995-04-20, release date: 1996-08-17, Last modification date: 2024-02-14)

Primary citation

Smith, C.A.,Rayment, I.
X-ray structure of the magnesium(II)-pyrophosphate complex of the truncated head of Dictyostelium discoideum myosin to 2.7 A resolution.
Biochemistry, 34:8973-8981, 1995

PubMed Abstract: 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.

PubMed: 7619796
DOI: 10.1021/bi00028a005

Experimental method

X-RAY DIFFRACTION (2.7 Å)