This study demonstrates that H2O2-mediated oxidative modification of the neuronal motor KIF1A reduces its processive motility in vitro, creates disulfide-linked multimers, and is partly reversible with reducing agents or cysteine substitutions.

By linking oxidative stress to impaired axonal transport via direct damage to a kinesin motor, the work provides a mechanistic, targetable connection between redox pathology and neurodegeneration that could motivate redox-modulating or motor-stabilizing therapeutic strategies for Parkinson's…

The kinesin-3 family member, KIF1A is an essential motor protein that carries out intracellular transport in neurons. Previous work has established that: 1) intracellular transport can be impaired in neurodegenerative diseases such as Alzheimer's and Parkinson's; and 2) oxidative stress is elevated in neurodegenerative diseases and during aging. To date there has not been a systematic study of the effects of reactive oxygen species on kinesin motor proteins. We hypothesized that oxidative stress can damage kinesin, leading to decreased motility. To test our hypothesis, we treated KIF1A in vitro with varying concentrations of hydrogen peroxide (H2O2), a common reactive oxygen species, and characterized the impacts on KIF1A function. Pretreatment of KIF1A with H2O2 at concentrations of 1 mM and higher decreased motility in microtubule gliding assays. In single-molecule assays KIF1A was impacted in two ways: a fraction of motors moved with slowed velocity, while a fraction of motors moved only diffusively with no net directionality. Non-reducing SDS-PAGE of oxidized kinesin showed higher molecular weight bands, consistent with disulfide-bonded dimers and higher-order species. Treating oxidized motors with reducing agents reversed this crosslinking and partially restored motility. Replacing cysteine residues in the motor domain reduced the effects of moderate oxidation but did not prevent the severe degradation of motility at the highest H2O2 concentrations, indicating there is irreversible oxidative damage beyond only cysteine residues. Our results suggest that KIF1A can be impacted by oxidative stress and raise the possibility that oxidized KIF1A may be involved in the pathogenesis of neurodegenerative diseases.