Cytoskeletal-driven membrane dynamics requires the concerted action of microtubules, actin, and their associated motors and activators. Although specific motors and adaptors have been identified that participate in the transport, tubulation, and retraction of biological membranes, the molecular mechanisms of many of these processes are not well defined. This gap in knowledge is due, in part, to the lack of understanding of the biophysical parameters of the key cytoskeletal components that drive these dynamic membrane events. Knowledge of these parameters allows formation of quantitative models that consider the mechanical and kinetic limits of protein function. Therefore, this subproject proposes to use single-molecule and ensemble biophysical techniques to measure directly the motile and mechanical properties of cytoplasmic dynein (mammalian and yeast) and kinesin (KIF16B) motors. Results will be correlated directly with new insights from analysis of motor structural dynamics obtained in collaboration with Dr. Goldman, and will provide the biophysical parameters required to better understand the cellular and in vitro experiments performed collaboration with Dr. Holzbaur. We will also determine mechanical properties of the key scaffolding proteins that link membranes, motors, and cytoskeletal filaments. These interactions include the attachment of KIF16B to phosphoinositides, the dynein-bicaudalD-Rab6-membrane complex, and the interaction of WHAMM with membranes. The results will be correlated directly to biochemical, structural, and cellular experiments performed in collaboration with Drs. Dominguez and Holzbaur. Our studies will provide the biophysical parameters required to generate quantitative models for the roles of cytoskeletal motors and scaffolding protein in powering membrane dynamics and transport.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Program Projects (P01)
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Special Emphasis Panel (ZRG1)
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University of Pennsylvania
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Hendricks, Adam G; Goldman, Yale E (2017) Measuring Molecular Forces Using Calibrated Optical Tweezers in Living Cells. Methods Mol Biol 1486:537-552
Kast, David J; Dominguez, Roberto (2017) The Cytoskeleton-Autophagy Connection. Curr Biol 27:R318-R326
Lippert, Lisa G; Dadosh, Tali; Hadden, Jodi A et al. (2017) Angular measurements of the dynein ring reveal a stepping mechanism dependent on a flexible stalk. Proc Natl Acad Sci U S A 114:E4564-E4573
Pyrpassopoulos, Serapion; Shuman, Henry; Ostap, E Michael (2017) Adhesion force and attachment lifetime of the KIF16B-PX domain interaction with lipid membranes. Mol Biol Cell 28:3315-3322
Lewis, John H; Jamiolkowski, Ryan M; Woody, Michael S et al. (2017) Deconvolution of Camera Instrument Response Functions. Biophys J 112:1214-1220
Greenberg, Michael J; Shuman, Henry; Ostap, E Michael (2017) Measuring the Kinetic and Mechanical Properties of Non-processive Myosins Using Optical Tweezers. Methods Mol Biol 1486:483-509
Woody, Michael S; Lewis, John H; Greenberg, Michael J et al. (2016) MEMLET: An Easy-to-Use Tool for Data Fitting and Model Comparison Using Maximum-Likelihood Estimation. Biophys J 111:273-282
McIntosh, Betsy B; Ostap, E Michael (2016) Myosin-I molecular motors at a glance. J Cell Sci 129:2689-95
Wilson, Meredith H; Bray, Matthew G; Holzbaur, Erika L F (2016) Methods for Assessing Nuclear Rotation and Nuclear Positioning in Developing Skeletal Muscle Cells. Methods Mol Biol 1411:269-90
Lippert, Lisa G; Hallock, Jeffrey T; Dadosh, Tali et al. (2016) NeutrAvidin Functionalization of CdSe/CdS Quantum Nanorods and Quantification of Biotin Binding Sites using Biotin-4-Fluorescein Fluorescence Quenching. Bioconjug Chem 27:562-8

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