TY - JOUR
T1 - Thermodynamic properties of the kinesin neck-region docking to the catalytic core
AU - Rice, S.
AU - Cui, Y.
AU - Sindelar, C.
AU - Naber, N.
AU - Matuska, M.
AU - Vale, R.
AU - Cooke, Roger
N1 - Funding Information:
We have used temperature-dependent EPR spectroscopy to determine the thermodynamic properties, Δ kJ/mol). The large, favorable enthalpy changes balanced out by large unfavorable entropy changes indicate that the neck linker docks to the core from an unstructured state, in a conformational change that is similar to a protein-folding transition. Kinesin uses only a small portion of its free energy available from ATP to generate a forward bias, a property that may enable it to be a very efficient motor. The kinesin neck linker undocks and undergoes a transition into a high-entropy state, which suggests the possibility that entropic strain plays an important role in generating the nearly unidirectional forward motility of the kinesin dimer. G , Δ H , and T Δ S associated with the AMPPNP-induced docking of the kinesin neck linker that generates its forward bias and drives motility. The free-energy changes associated with the neck-linker conformational change were favorable but small (∼3 The authors acknowledge P. O’Farrell for discussions of the properties of random coil polymers and E. Pate for helpful discussions of the manuscript. S. Rice is supported by a Walter V. and Idun Berry Fellowship. This work was supported by a National Institutes of Health program project grant.
PY - 2003/3/1
Y1 - 2003/3/1
N2 - Kinesin motors move on microtubules by a mechanism that involves a large, ATP-triggered conformational change in which a mechanical element called the neck linker docks onto the catalytic core, making contacts with the core throughout its length. Here, we investigate the thermodynamic properties of this conformational change using electron paramagnetic resonance (EPR) spectroscopy. We placed spin probes at several locations on the human kinesin neck linker and recorded EPR spectra in the presence of microtubules and either 5′-adenylylimidodiphosphate (AMPPNP) or ADP at temperatures of 4-30°C. The free-energy change (ΔG) associated with AMPPNP-induced docking of the neck linker onto the catalytic core is favorable but small, about 3 kJ/mol. In contrast, the favorable enthalpy change (ΔH) and unfavorable entropy change (TΔS) are quite large, about 50 kJ/mol. A mutation in the neck linker, V331A/N332A, results in an unfavorable ΔG for AMPPNP-induced zipping of the neck linker onto the core and causes motility defects. These results suggest that the kinesin neck linker folds onto the core from a more unstructured state, thereby paying a large entropic cost and gaining a large amount of enthalpy.
AB - Kinesin motors move on microtubules by a mechanism that involves a large, ATP-triggered conformational change in which a mechanical element called the neck linker docks onto the catalytic core, making contacts with the core throughout its length. Here, we investigate the thermodynamic properties of this conformational change using electron paramagnetic resonance (EPR) spectroscopy. We placed spin probes at several locations on the human kinesin neck linker and recorded EPR spectra in the presence of microtubules and either 5′-adenylylimidodiphosphate (AMPPNP) or ADP at temperatures of 4-30°C. The free-energy change (ΔG) associated with AMPPNP-induced docking of the neck linker onto the catalytic core is favorable but small, about 3 kJ/mol. In contrast, the favorable enthalpy change (ΔH) and unfavorable entropy change (TΔS) are quite large, about 50 kJ/mol. A mutation in the neck linker, V331A/N332A, results in an unfavorable ΔG for AMPPNP-induced zipping of the neck linker onto the core and causes motility defects. These results suggest that the kinesin neck linker folds onto the core from a more unstructured state, thereby paying a large entropic cost and gaining a large amount of enthalpy.
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U2 - 10.1016/S0006-3495(03)74992-3
DO - 10.1016/S0006-3495(03)74992-3
M3 - Article
C2 - 12609886
AN - SCOPUS:0037342516
VL - 84
SP - 1844
EP - 1854
JO - Biophysical Journal
JF - Biophysical Journal
SN - 0006-3495
IS - 3
ER -