The structural switch of nucleotide-free kinesin

Sci Rep. 2017 Feb 14:7:42558. doi: 10.1038/srep42558.

Abstract

Kinesin-1 is an ATP-dependent motor protein that moves towards microtubules (+)-ends. Whereas structures of isolated ADP-kinesin and of complexes with tubulin of apo-kinesin and of ATP-like-kinesin are available, structural data on apo-kinesin-1 in the absence of tubulin are still missing, leaving the role of nucleotide release in the structural cycle unsettled. Here, we identified mutations in the kinesin nucleotide-binding P-loop motif that interfere with ADP binding. These mutations destabilize the P-loop (T87A mutant) or magnesium binding (T92V), highlighting a dual mechanism for nucleotide release. The structures of these mutants in their apo form are either isomorphous to ADP-kinesin-1 or to tubulin-bound apo-kinesin-1. Remarkably, both structures are also obtained from the nucleotide-depleted wild-type protein. Our results lead to a model in which, when detached from microtubules, apo-kinesin possibly occupies the two conformations we characterized, whereas, upon microtubule binding, ADP-kinesin converts to the tubulin-bound apo-kinesin conformation and releases ADP. This conformation is primed to bind ATP and, therefore, to run through the natural nucleotide cycle of kinesin-1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Diphosphate / chemistry
  • Adenosine Diphosphate / metabolism
  • Humans
  • Kinesins / chemistry
  • Kinesins / genetics
  • Kinesins / metabolism*
  • Microtubules / chemistry
  • Microtubules / metabolism
  • Models, Biological
  • Models, Molecular
  • Molecular Conformation
  • Mutation
  • Nucleotides / chemistry
  • Nucleotides / metabolism
  • Protein Binding
  • Tubulin / chemistry
  • Tubulin / metabolism

Substances

  • Nucleotides
  • Tubulin
  • Adenosine Diphosphate
  • Kinesins