X-ray structure of the magnesium(II).ADP.vanadate complex of the Dictyostelium discoideum myosin motor domain to 1.9 A resolution.

摘要: The structure of the vanadate-trapped ADP complex a truncated head Dictyostelium myosin II consisting residues Asp 2-Asn 762 has been determined by molecular replacement at 1.9 A resolution and refined to crystallographic R-factor 19.4%. crystals belong orthorhombic space group C2221 where = 84.50 A, b 145.4 c 152.8 A. conformation protein is similar that MgADP.AlF4.SlDc [Fisher, A.J., et al. (1995) Biochemistry 34, 8960-8972]. nucleotide binding site contains between MgADP vanadate exhibits very seen in previous complexes. ion adopts trigonal bipyramidal coordination. three equatorial oxygen ligands are fairly short, average 1.7 relative single bond distance approximately 1.8 coordinated magnesium ion, N zeta Lys 185, five other ligands. apical coordination filled terminal on beta-phosphate water molecule distances 2.1 2.3 respectively. long length bonds suggests order considerably less than unity. This confirms earlier suggestion model for transition state ATP hydrolysis thus provides insight into those factors responsible catalysis. In particular, it shows surrounding gamma-phosphate pocket oriented stabilize an appropriate position in-line nucleophilic attack gamma-phosphorus ATP. reveals also orientation COOH-terminal region beyond Thr 688 which different from observed either MgADP.BeFx.SlDc or chicken skeletal subfragment 1. consistent with playing important role transduction chemical energy mechanical movement.