Secondary Structure and Compliance of a Predicted Flexible Domain in Kinesin-1 Necessary for Cooperation of Motors

• Published in: Biophysical journal Vol. 95; no. 11; pp. 5216 - 5227
• Main Authors: Crevenna, Alvaro H., Madathil, Sineej, Cohen, Daniel N., Wagenbach, Michael, Fahmy, Karim, Howard, Jonathon
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.12.2008; The Biophysical Society
• Subjects: Amino Acid Sequence; Animals; Assaying; Cooperation; Deletion; Drosophila Proteins - chemistry; Drosophila Proteins - metabolism; Elasticity; Fluorescence; Gliding; Hinges; Humans; Kinesin - chemistry; Kinesin - metabolism; Mice; Microtubules - metabolism; Molecular Sequence Data; Motors; Movement; Muscle and Contractility; Peptides; Peptides - chemistry; Peptides - metabolism; Protein Multimerization; Protein Stability; Protein Structure, Quaternary; Protein Structure, Secondary; Protein Structure, Tertiary; Temperature
• ISSN: 0006-3495; 1542-0086
• DOI: 10.1529/biophysj.108.132449

Although the mechanism by which a kinesin-1 molecule moves individually along a microtubule is quite well-understood, the way that many kinesin-1 motor proteins bound to the same cargo move together along a microtubule is not. We identified a 60-amino-acid-long domain, termed Hinge 1, in kinesin-1 from Drosophila melanogaster that is located between the coiled coils of the neck and stalk domains. Its deletion reduces microtubule gliding speed in multiple-motor assays but not single-motor assays. Hinge 1 thus facilitates the cooperation of motors by preventing them from impeding each other. We addressed the structural basis for this phenomenon. Video-microscopy of single microtubule-bound full-length motors reveals the sporadic occurrence of high-compliance states alternating with longer-lived, low-compliance states. The deletion of Hinge 1 abolishes transitions to the high-compliance state. Based on Fourier transform infrared, circular dichroism, and fluorescence spectroscopy of Hinge 1 peptides, we propose that low-compliance states correspond to an unexpected structured organization of the central Hinge 1 region, whereas high-compliance states correspond to the loss of that structure. We hypothesize that strain accumulated during multiple-kinesin motility populates the high-compliance state by unfolding helical secondary structure in the central Hinge 1 domain flanked by unordered regions, thereby preventing the motors from interfering with each other in multiple-motor situations.