A highly conserved 3 ₁₀ helix within the kinesin motor domain is critical for kinesin function and human health

Abstract

KIF1A is a critical cargo transport motor within neurons. More than 100 known mutations result in KIF1A-associated neurological disorder (KAND), a degenerative condition for which there is no cure. A missense mutation, P305L, was identified in children diagnosed with KAND, but the molecular basis for the disease is unknown. We find that this conserved residue is part of an unusual 310 helix immediately adjacent to the family-specific K-loop, which facilitates a high microtubule-association rate. We find that the mutation negatively affects several biophysical parameters of the motor. However, the microtubule-association rate of the motor is most markedly affected, revealing that the presence of an intact K-loop is not sufficient for its function. We hypothesize that the 310 helix facilitates a specific K-loop conformation that is critical for its function. We find that the function of this proline is conserved in kinesin-1, revealing a fundamental principle of the kinesin motor mechanism.

Force generation of KIF1C is impaired by pathogenic mutations

“…Most KIF1C stalls last several 100 ms, while only 20% of hyperactive KIF1A stalls exceed 50 ms. 17 While KIF1C has a 3.5-fold increased probability of backward slipping under load compared with KHC, constitutively active KIF1A shows 50-fold enhanced slipping. 17 , 23 Thus, our data suggest that KIF1C has unique force-generating properties that are intermediate between KIF1A and kinesin-1. These intermediate properties might enable KIF1C to be both highly processive 10 and generate substantial forces at low motor numbers, which might explain why KIF1C has been identified as the most effective cellular cargo transporter.…”

“…However, we found that the unloaded velocity of the motors was not negatively affected and even slightly increased, while mutations across the microtubule-binding interface of KIF1A resulted in lower single-molecule velocities. 23 , 26 , 30 Alanine scanning mutagenesis in kinesin-1 also identified two mutations (E220A and L317A) with a slightly higher velocity but reduced microtubule affinity. 31 Thus, the different outcome of reducing microtubule affinity on unloaded speed across kinesin-3 motors could be due to the biophysical properties of KIF1C being intermediate between kinesin-1 and KIF1A.…”

“… 26 Thus, our findings that the two pathogenic mutations in KIF1C retain motility but with reduced run length is consistent with this. Pathogenic mutations in other regions of the microtubule-binding interface of KIF1A 23 , 30 also showed reduced run lengths. However, we found that the unloaded velocity of the motors was not negatively affected and even slightly increased, while mutations across the microtubule-binding interface of KIF1A resulted in lower single-molecule velocities.…”

Control of Motor Landing and Processivity by the CAP-Gly Domain in the KIF13B Tail

“…In addition, the CAP-Gly domain mediates higher landing rates and an approximately 3-fold longer run length on tyrosinated versus detyrosinated MTs. Given that defects in kinesin-3's interactions with microtubules underly human neurodevelopmental and neurodegenerative diseases 64,65 , our results provide new insights into the various strategies adopted by kinesin-3 motors to augment the ability of the motor domains to move processively along microtubules to support cellular trafficking homeostasis and human health.…”

Microtubule Lattice Spacing Governs Cohesive Envelope Formation of Tau Family Proteins

“…We also examined the processive kinesin-3 family member, KIF1A, which is known to transport cargo within neurons. Regulation of KIF1A transport within neurons is critical for human health as evidenced by a large cohort of human mutations in KIF1A that result in the neurodegenerative disorder KIF1A-associated neurological disease (KAND) (Boyle et al, 2021;Budaitis et al, 2021;Chiba et al, 2019;Lam et al, 2021). KIF1A has also been reported to be sensitive to the nucleotide state, and by extension possibly the dimer compaction state, of the microtubule lattice on which it travels (Guedes-Dias et al, 2019).…”