Cryo-EM structure of the Ustilago maydis kinesin-5 motor domain bound to microtubules.

(2019) J Struct Biol 

• PubMed: 31288039 Search on PubMedSearch on PubMed Central
• DOI: https://doi.org/10.1016/j.jsb.2019.07.003
• Primary Citation Related Structures: 
  5MM4, 5MM7


• PubMed Abstract: 
  

  In many eukaryotes, kinesin-5 motors are essential for mitosis, and small molecules that inhibit human kinesin-5 disrupt cell division. To investigate whether fungal kinesin-5s could be targets for novel fungicides, we studied kinesin-5 from the pathogenic fungus Ustilago maydis. We used cryo-electron microscopy to determine the microtubule-bound structure of its motor domain with and without the N-terminal extension. The ATP-like conformations of the motor in the presence or absence of this N-terminus are very similar, suggesting this region is structurally disordered and does not directly influence the motor ATPase. The Ustilago maydis kinesin-5 motor domain adopts a canonical ATP-like conformation, thereby allowing the neck linker to bind along the motor domain towards the microtubule plus end. However, several insertions within this motor domain are structurally distinct. Loop2 forms a non-canonical interaction with α-tubulin, while loop8 may bridge between two adjacent protofilaments. Furthermore, loop5 - which in human kinesin-5 is involved in binding allosteric inhibitors - protrudes above the nucleotide binding site, revealing a distinct binding pocket for potential inhibitors. This work highlights fungal-specific elaborations of the kinesin-5 motor domain and provides the structural basis for future investigations of kinesins as targets for novel fungicides.

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Organizational Affiliation: 
• Institute of Structural and Molecular Biology, Birkbeck College, London WC1E 7HX, UK.
Institute of Structural and Molecular Biology, Birkbeck College, London WC1E 7HX, UK. Electronic address: c.moores@mail.cryst.bbk.ac.uk.
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