5M5M

Pseudo-atomic model of microtubule-bound S.pombe kinesin-5 motor domain in the AMPPNP state (based on cryo-electron microscopy experiment): the N-terminus adopts multiple conformations.

Summary for 5M5M

• Entry DOI: 10.2210/pdb5m5m/pdb
• EMDB information: 3445
• Descriptor: Tubulin alpha-1D chain, Tubulin beta-2B chain, Kinesin-like protein cut7, ... (8 entities in total)
• Functional Keywords: microtubule-bound s.pombe kinesin-5, motor domain, amppnp bound state, modeller 9.10 2013-08 complex, motor protein
• Biological source: Schizosaccharomyces pombe (strain 972 / ATCC 24843) (Fission yeast); More
• Cellular location: Cytoplasm, cytoskeleton : Q2HJ86 Q6B856; Cytoplasm, cytoskeleton, microtubule organizing center, spindle pole body: P24339
• Total number of polymer chains: 3
• Total formula weight: 143256.74

Authors

Goulet, A.,Moores, C.A.,Cross, R.A. (deposition date: 2016-10-21, release date: 2016-11-30, Last modification date: 2024-05-08)

Primary citation

Britto, M.,Goulet, A.,Rizvi, S.,von Loeffelholz, O.,Moores, C.A.,Cross, R.A.
Schizosaccharomyces pombe kinesin-5 switches direction using a steric blocking mechanism.
Proc. Natl. Acad. Sci. U.S.A., 113:E7483-E7489, 2016

PubMed Abstract: Cut7, the sole kinesin-5 in Schizosaccharomyces pombe, is essential for mitosis. Like other yeast kinesin-5 motors, Cut7 can reverse its stepping direction, by mechanisms that are currently unclear. Here we show that for full-length Cut7, the key determinant of stepping direction is the degree of motor crowding on the microtubule lattice, with greater crowding converting the motor from minus end-directed to plus end-directed stepping. To explain how high Cut7 occupancy causes this reversal, we postulate a simple proximity sensing mechanism that operates via steric blocking. We propose that the minus end-directed stepping action of Cut7 is selectively inhibited by collisions with neighbors under crowded conditions, whereas its plus end-directed action, being less space-hungry, is not. In support of this idea, we show that the direction of Cut7-driven microtubule sliding can be reversed by crowding it with non-Cut7 proteins. Thus, crowding by either dynein microtubule binding domain or Klp2, a kinesin-14, converts Cut7 from net minus end-directed to net plus end-directed stepping. Biochemical assays confirm that the Cut7 N terminus increases Cut7 occupancy by binding directly to microtubules. Direct observation by cryoEM reveals that this occupancy-enhancing N-terminal domain is partially ordered. Overall, our data point to a steric blocking mechanism for directional reversal through which collisions of Cut7 motor domains with their neighbors inhibit their minus end-directed stepping action, but not their plus end-directed stepping action. Our model can potentially reconcile a number of previous, apparently conflicting, observations and proposals for the reversal mechanism of yeast kinesins-5.

PubMed: 27834216
DOI: 10.1073/pnas.1611581113

Experimental method

ELECTRON MICROSCOPY (9.3 Å)