Kinetic characterization of the weak binding states of myosin V

Christopher M. Yengo, Enrique M. De La Cruz, Daniel Safer, E. Michael Ostap, H. Lee Sweeney

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Myosin V is a molecular motor shown to move processively along actin filaments. We investigated the properties of the weak binding states of monomeric myosin V containing a single IQ domain (MV 1IQ) to determine if the affinities of these states are increased as compared to conventional myosin. Further, using a combination of non-hydrolyzable nucleotide analogues and mutations that block ATP hydrolysis, we sought to probe the states that are populated during ATP-induced dissociation of actomyosin. MV 1IQ binds actin with a Kd = 4 μM in the presence of ATPγS at 50 mM KC1, which is 10-20-fold tighter than that of nonprocessive class II myosins. Mutations within the switch II region trapped MV 1IQ in two distinct M.ATP states with very different actin binding affinities (Kd = 0.2 and 2 μM). Actin binding may change the conformation of the switch II region, suggesting that elements of the nucleotide binding pocket will be in a different conformation when bound to actin than is seen in any of the myosin crystal structures to date.

Original languageEnglish (US)
Pages (from-to)8508-8517
Number of pages10
Issue number26
StatePublished - Jul 2 2002

All Science Journal Classification (ASJC) codes

  • Biochemistry


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