About

William Hancock is a Professor of Biomedical Engineering at Penn State University, affiliated with the College of Engineering. His research focuses on cell and molecular bioengineering, with specific interests in kinesin molecular motors, microtubules, molecular biomechanics, nanoscale biomolecular transport, and directed assembly. Hancock's work involves understanding the mechanistic and kinetic aspects of motor proteins and their roles in intracellular transport, microtubule dynamics, and enzyme activity. He has contributed to the field through numerous publications that explore the biophysical mechanisms underlying motor protein function, microtubule growth, and cellular transport processes.

Research topics

• Chemistry
• Biology
• Biochemistry
• Cell biology
• Biophysics
• Materials science
• Nanotechnology
• Physics
• Organic chemistry
• Optics
• Genetics
• Biological system

Selected publications

• DNA tensiometer reveals catch-bond detachment kinetics of kinesin-1, -2 and -3

  eLife · 2026-03-26

  articleOpen accessSenior author

  Bidirectional cargo transport by kinesin and dynein is essential for cell viability and defects are linked to neurodegenerative diseases. Computational modeling suggests that the load-dependent off-rate is the strongest determinant of which motor ‘wins’ a kinesin-dynein tug-of-war, and optical tweezer experiments find family-dependent differences in the sensitivity of detachment to load, with kinesin-3 > kinesin-2 > kinesin-1. However, in reconstituted kinesin-dynein pairs vitro, all three kinesin families compete nearly equally well against dynein. Modeling and experiments have confirmed that vertical forces inherent to the large trapping beads enhance kinesin-1 dissociation rates. In vivo, vertical forces are expected to range from negligible to dominant, depending on cargo and microtubule geometries. To investigate the detachment and reattachment kinetics of kinesin-1, 2 and 3 motors against loads oriented parallel to the microtubule, we created a DNA tensiometer comprising a DNA entropic spring attached to the microtubule on one end and a motor on the other. Kinesin dissociation rates at stall were slower than detachment rates during unloaded runs, and the complex reattachment kinetics were consistent with a weakly-bound ‘slip’ state preceding detachment. Kinesin-3 behaviors under load suggested that long KIF1A run lengths result from the concatenation of multiple short runs connected by diffusive episodes. Stochastic simulations were able to recapitulate the load-dependent detachment and reattachment kinetics for all three motors and provide direct comparison of key transition rates between families. These results provide insight into how kinesin-1, -2 and -3 families transport cargo in complex cellular geometries and compete against dynein during bidirectional transport.

  PublisherDOI

• Oxidative stress impairs processive motility of the axonal transport motor KIF1A

  Journal of Biological Chemistry · 2026-04-17

  articleOpen accessSenior author

  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 (H 2 O 2 ), a common reactive oxygen species, and characterized the impacts on KIF1A function.Pretreatment of KIF1A with H 2 O 2 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 H 2 O 2 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.

  PublisherOA PDFDOI

• Oxidative stress impairs processive motility of the axonal transport motor KIF1A

  ScholarSphere (Penn State Libraries) · 2026-03-25

  datasetOpen access1st authorCorresponding

  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.

  PublisherOA PDFDOI

• BPS2026 – Architecture of HIV-1 capsid bound to the dynein transport machinery

  Biophysical Journal · 2026-02-01

  article
  PublisherDOI

• Dimeric Cin8 motors have an inherent plus-end bias and weak interhead coordination

  Biophysical Journal · 2026-03-07

  articleSenior author
  PublisherDOI

• Protocol to reconstitute motor protein clustering on vesicle membranes using a DNA scaffold-based system in vitro

  STAR Protocols · 2026-03-01

  articleOpen accessSenior author

  Cytoskeletal motor proteins drive long-range intracellular transport, but how their organization on vesicle membranes affects motility remains poorly understood. Here, we present a protocol to reconstitute kinesin-1 clustering on synthetic liposomes using a DNA-based scaffold. We describe steps for functionalizing liposomes with kinesin-1, inducing DNA-mediated motor clusters, and analyzing liposome motility on surface-immobilized microtubules. This protocol enables quantitative investigation of motor organization in vesicle transport and is adaptable to other cytoskeletal motors. For complete details on the use and execution of this protocol, please refer to Jiang et al. 1 • Steps for assembling and isolating kinesin-functionalized liposomes • Procedures for inducing and verifying motor clustering on liposome surfaces • Guidance on quantifying motor number and comparing motility of clustered motors Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics. Cytoskeletal motor proteins drive long-range intracellular transport, but how their organization on vesicle membranes affects motility remains poorly understood. Here, we present a protocol to reconstitute kinesin-1 clustering on synthetic liposomes using a DNA-based scaffold. We describe steps for functionalizing liposomes with kinesin-1, inducing DNA-mediated motor clusters, and analyzing liposome motility on surface-immobilized microtubules. This protocol enables quantitative investigation of motor organization in vesicle transport and is adaptable to other cytoskeletal motors.

  PublisherDOI

• DNA tensiometer reveals catch-bond detachment kinetics of kinesin-1, -2 and -3

  ScholarSphere (Penn State Libraries) · 2026-05-13

  articleOpen access1st authorCorresponding

  Bidirectional cargo transport by kinesin and dynein is essential for cell viability, and defects are linked to neurodegenerative disease. Computational models predict that load-dependent motor detachment strongly determines the outcome of kinesin–dynein tug-of-war, with kinesin-3 and kinesin-2 more load-sensitive than kinesin-1. Yet reconstituted assays show that all three kinesin families compete similarly against dynein. Previous work demonstrated that vertical forces from optical trapping assays can enhance kinesin-1 dissociation, suggesting that motor behavior may depend strongly on cargo geometry. To measure kinesin detachment and reattachment kinetics under forces applied parallel to the microtubule, we developed a DNA-based tensiometer using an entropic DNA spring linking motors to microtubules. For kinesin-1, -2, and -3, dissociation rates at stall were slower than during unloaded motion, and reattachment kinetics were consistent with a weakly bound slip state preceding detachment. Kinesin-3 behavior further suggested that long KIF1A run lengths arise from multiple short runs connected by diffusive episodes. Stochastic simulations reproduced the measured load-dependent kinetics and enabled direct comparison of transition rates among kinesin families. These results provide insight into how kinesin-1, -2 and -3 transport cargo in complex cellular geometries and compete against dynein during bidirectional transport.

  PublisherDOI

• Dimeric Cin8 motors have an inherent plus-end bias and weak inter-head coordination

  ScholarSphere (Penn State Libraries) · 2026-01-26

  datasetOpen access1st authorCorresponding

  Kinesin-5 motors are bipolar tetramers that crosslink and slide antiparallel microtubules during mitotic spindle assembly. Fungal kinesin-5 motors, such as Cin8, exhibit bidirectional motility, switching between minus- and plus-end-directed stepping in response to environmental conditions; however, the molecular basis of this directional switching remains unclear. To better understand the origin of this bidirectional behavior, we investigated the motility and ATPase kinetics of Cin8 dimers, created by fusing the motor domains to a stable coiled-coil domain from kinesin-1. To investigate the role of the proximal neck coiled-coil region in coordinating motor activity and directionality, we engineered Cin8 dimers that included the first four heptads of the Cin8 neck-coil domain. By analyzing the stepping kinetics, microtubule residence times, and directional switching dynamics, we found that these Cin8 dimers move processively with a net plus-end directionality along with undirected movements, behaviors that mimic the plus-ended motility state of wild-type Cin8. However, fast minus-ended motility seen in wild-type Cin8 tetramers was not observed in the dimers. The instantaneous velocity distributions and ATPase rates were inconsistent with the undirected movement being solely due to passive diffusion, suggesting that they reflect random bidirectional stepping. Fewer undirected movements were seen on yeast microtubules, their native physiological substrate, compared to on bovine microtubules. Replacing the Cin8 neck-coil domain with a stable coiled-coil led to faster plus-end stepping, fewer undirected movements, a reduction in the microtubule binding duration, and enhanced coupling between ATP hydrolysis and plus-end stepping. This behavior suggests that the native Cin8 neck coil confers flexibility between the two motor domains that enhances occupancy of a two-heads-bound state during the chemomechanical cycle. Our results suggest that flexibility between the two motor domains of Cin8 contributes to bidirectional stepping, and that sustained minus-end movement requires regions outside the motor domain.

  PublisherDOI

• The Carbohydrate Binding Module of TrCel7A Aids in Navigating the Complexity of Plant Cell Walls

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-09-18

  preprint

  Abstract Efficient enzymatic deconstruction of plant cell walls is critical for utilization of lignocellulose biomass. Key enzymes in this process are cellobiohydrolases, a class of cellulases that processively degrade crystalline cellulose. Many cellobiohydrolases possess a carbohydrate-binding module (CBM), yet the importance of CBMs in substrate interaction remains unclear. Here, we use single-molecule fluorescence microscopy to investigate how CBM1 of Trichoderma reesei Cel7A influences enzyme binding and motility on cellulose substrates of varying complexity. We compare wild-type Cel7A with a truncated variant lacking CBM1 (Cel7A ΔCBM ) on bacterial cellulose (BC), phosphoric acid swollen cellulose (PASC), delignified milkweed cellulose (MWC), and holocellulose nanofibrils (hCNF). While both variants showed similar steady-state binding densities on BC and PASC, Cel7A ΔCBM exhibited reduced binding on MWC and hCNF, with the greatest reduction on the hemicellulose-rich hCNF. Alkali removal of hemicellulose partially restored Cel7A ΔCBM binding, suggesting a role for CBM1 in substrate navigation and productive binding sites recognition. Kinetic analyses revealed that CBM1 enables a rapid binding mode absent in the truncated variant. Comparisons with isolated CBM3 further showed that CBMs are capable of fast substrate association. These findings demonstrate that CBMs enhance cellulase-substrate interactions by accelerating binding, enabling navigation of the complex environment of plant cell walls. Our results emphasize the importance of CBMs in natural cellobiohydrolase function and highlight their value in the design of improved cellulases for industrial biomass conversion.

  PublisherDOI

• Motor clustering enhances kinesin-driven vesicle transport

  Biophysical Journal · 2025-05-05 · 2 citations

  articleSenior author
  PublisherDOI

Recent grants

• Molecular mechanism of bidirectional transport

  NIH · $4.9M · 2021–2030

• NIH Grant R01GM100076

  NIH · $1.7M · 2017

• Biophotonics: Molecular Motor Biophotonics

  NSF · $537k · 2003–2007

• Multimotor Mechanisms in Microtubule-based Transport

  NIH · $1.3M · 2017–2023

• Enhancing cellulase activity through single-molecule imaging and protein engineering as a testbed for understanding and improving enzymatic deconstruction of insoluble substrates

  NSF · $630k · 2023–2027

Frequent coauthors

• Keith J. Mickolajczyk

  Rutgers, The State University of New Jersey

  31 shared

• Luke M. Rice

  The University of Texas Southwestern Medical Center

  21 shared

• Erkan Tüzel

  Temple University

  21 shared

• Allison M. Gicking

  Pennsylvania State University

  21 shared

• Joseph M. Cleary

  Pennsylvania State University

  20 shared

• Qingzhou Feng

  19 shared

• Shankar Shastry

  University of California, Santa Cruz

  18 shared

• Daguan Nong

  Pennsylvania State University

  16 shared