The Overall Conformation of Conventional Kinesins Studied by Small Angle X-ray and Neutron Scattering

Frank Kozielski,Dmitri Svergun,Giuseppe Zaccaı̈,Richard H Wade,Michel H.J Koch

doi:10.1074/jbc.m007169200

Abstract

The quaternary structures of several monomeric and dimeric kinesin constructs from Homo sapiens and Drosophila melanogaster were analyzed using small angle x-ray and neutron scattering. The experimental scattering curves of these proteins were compared with simulated scattering curves calculated from available crystallographic coordinates. These comparisons indicate that the overall conformations of the solution structures of D. melanogaster and H. sapiens kinesin heavy chain dimers are compatible with the crystal structure of dimeric kinesin from Rattus norvegicus. This suggests that the unusual asymmetric conformation of dimeric kinesin in the microtubule-independent ADP state is likely to be a general feature of the kinesin heavy chain subfamily. An intermediate length Drosophila construct (365 residues) is mostly monomeric at low protein concentration whereas at higher concentrations it is dimeric with a tendency to form higher oligomers.

Highlights

Motor proteins such as dyneins, myosins, and kinesins convert the energy of ATP hydrolysis into mechanical work
The experimental scattering curves of these proteins were compared with simulated scattering curves calculated from available crystallographic coordinates. These comparisons indicate that the overall conformations of the solution structures of D. melanogaster and H. sapiens kinesin heavy chain dimers are compatible with the crystal structure of dimeric kinesin from Rattus norvegicus
This suggests that the unusual asymmetric conformation of dimeric kinesin in the microtubule-independent ADP state is likely to be a general feature of the kinesin heavy chain subfamily

Summary

Introduction

Motor proteins such as dyneins, myosins, and kinesins convert the energy of ATP hydrolysis into mechanical work. The heavy chains have a three-domain structure; the globular N-terminal motor domain, which contains the ATP- and microtubule-binding sites, is about 340 amino acids long. The crystal structures are known for the motor domain itself [12,13] and for one functional dimer [14], both in the microtubule-independent ADP form. It contains one tightly bound MgADP molecule in the active site These crystal structures and those of ncd [15,16,17] have revealed important features and in particular the very high structural similarity of the motor domains of different members of the kinesin superfamily. If the asymmetric conformation found in the crystal exists in solution, there would be at least a hint as to whether or not kinesin changes its conformation upon binding to microtubules

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