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Atomic models of the myosin motor domain with different bound nucleotides have revealed the open and closed con-formationsof the switch2 element [Geeves,M.A.&Holmes, K.C. (1999)Annu. Rev. Biochem.68, 687–728]. The two conformations are in dynamic equilibrium, which is con-trolled by the bound nucleotide. In the present work we attempted to characterize the flexibilityof themotor domain in the open and closed conformations in rabbit skeletal myosin subfragment 1. | Eur. J. Biochem. 270 4835-4845 2003 FEBS 2003 doi 10.1046 j.1432-1033.2003.03883.x Dynamic reorganization of the motor domain of myosin subfragment 1 in different nucleotide states Emôke Bodis1 Krisztina Szarka2 Miklos Nyitrai2 and Bela Somogyi1 2 1 Department of Biophysics Faculty of Medicine University of Pecs Hungary 2Research Group for Fluorescence Spectroscopy Office for Academy Research Groups Attached to Universities and Other Institutions Department of Biophysics Faculty of Medicine University of Pecs Hungary Atomic models of the myosin motor domain with different bound nucleotides have revealed the open and closed conformations of the switch 2 element Geeves M.A. Holmes K.C. 1999 Annu. Rev. Biochem. 68 687-728 . The two conformations are in dynamic equilibrium which is controlled by the bound nucleotide. In the present work we attempted to characterize the flexibility of the motor domain in the open and closed conformations in rabbit skeletal myosin subfragment 1. Three residues Ser181 Lys553 and Cys707 were labelled with fluorophores and the probes identified three fluorescence resonance energy transfer pairs. The effect of ADP ADP.BeFx ADP.AlF- and ADP.Vi on the conformation of the motor domain was shown by applying temperature-dependent fluorescence resonance energy transfer methods. The 50 kDa lower domain was found to maintain substantial rigidity in both the open and closed conformations to provide the structural basis of the interaction of myosin with actin. The flexibility of the 50 kDa upper domain was high in the open conformation and further increased in the closed conformation. The converter region of subfragment 1 became more rigid during the open-to-closed transition the conformational change of which can provide the mechanical basis of the energy transduction from the nucleotide-binding pocket to the lightchain-binding domain. Keywords protein dynamics and conformation myosin muscle nucleotides fluorescence resonance energy transfer. The .
