Kinesin Walks the Line: Single Motors Observed by Atomic Force Microscopy

• Published in: Biophysical journal Vol. 100; no. 10; pp. 2450 - 2456
• Main Authors: Schaap, Iwan A.T., Carrasco, Carolina, de Pablo, Pedro J., Schmidt, Christoph F.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 18.05.2011; Biophysical Society; The Biophysical Society
• Subjects: Actin Cytoskeleton - drug effects; Actin Cytoskeleton - metabolism; adenosine triphosphate; Adenosine Triphosphate - pharmacology; Adenylyl Imidodiphosphate - pharmacology; Atomic force microscopy; ATP; Binding sites; Biophysics; Cells; Computer Simulation; Cytoskeleton; Dimers; Humans; image analysis; Imaging; Immobilized Proteins - metabolism; kinesin; Kinesin - chemistry; Kinesin - metabolism; Microscopy; Microscopy, Atomic Force - methods; microtubules; Microtubules - drug effects; Microtubules - metabolism; molecular motor proteins; Motors; Muscle, Motility, and Motor Protein; Neurospora crassa - drug effects; Neurospora crassa - metabolism; Nucleotides; Physiology; Protein Binding - drug effects; Protein Multimerization - drug effects; Protein Transport - drug effects; Proteins; Transport
• ISSN: 0006-3495; 1542-0086
• DOI: 10.1016/j.bpj.2011.04.015

Motor proteins of the kinesin family move actively along microtubules to transport cargo within cells. How exactly a single motor proceeds on the 13 narrow lanes or protofilaments of a microtubule has not been visualized directly, and there persists controversy on the relative position of the two kinesin heads in different nucleotide states. We have succeeded in imaging Kinesin-1 dimers immobilized on microtubules with single-head resolution by atomic force microscopy. Moreover, we could catch glimpses of single Kinesin-1 dimers in their motion along microtubules with nanometer resolution. We find in our experiments that frequently both heads of one dimer are microtubule-bound at submicromolar ATP concentrations. Furthermore, we could unambiguously resolve that both heads bind to the same protofilament, instead of straddling two, and remain on this track during processive movement.