15 A resolution model of the monomeric kinesin motor, KIF1A.
A two-headed structure has been widely believed to be essential for the kinesin molecular motor to move processively on the track, microtubules. However, we have recently demonstrated that a monomeric motor domain construct of KIF1A (C351), a kinesin superfamily protein, moves processively, taking about 700 steps before being detached from microtubules. To elucidate the mechanism of its single-headed processivity, we examined the C351 -MT interaction by mutant analysis and high-resolution cryo-EM. Mutant analysis indicated the importance of a highly positively charged loop, the "K loop," for such processivity. A 15 A resolution structure unambiguously docked with the available atomic models revealed "K loop" as an extra microtubule-binding domain specific to KIF1A, and bound to the C terminus of tubulin. The site-specific cross-linking further confirmed this model.
Kikkawa
M
M
Department of Cell Biology, Graduate School of Medicine, University of Tokyo, Japan.
Okada
Y
Y
Hirokawa
N
N
D000818:Animals; D001665:Binding Sites / Q000502:physiology; D003432:Cross-Linking Reagents / Q000737:chemistry / Q000378:metabolism; D006046:Gold / Q000737:chemistry; D006801:Humans; D007091:Image Processing, Computer-Assisted; D016547:Kinesins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D008854:Microscopy, Electron; D008870:Microtubules / Q000737:chemistry / Q000648:ultrastructure; D008956:Models, Chemical; D020409:Molecular Motor Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D014404:Tubulin / Q000737:chemistry / Q000378:metabolism
D003432:Cross-Linking Reagents; C094065:KIF1A protein, human; D020409:Molecular Motor Proteins; D009419:Nerve Tissue Proteins; D014404:Tubulin; D006046:Gold; D016547:Kinesins