Faculty Profile

Megan Valentine

Assistant Professor

Contacts

Room 2361C
Engineering II Building
Santa Barbara, CA 93106-5070

tel: 805-893-2594
fax: 805-893-8651
valentine@engineering.ucsb.edu

Personal web site

Research Description

Our experiments employ state-of-the-art nanoscale manipulation and measurement techniques to probe diverse biological materials on length scales from that of single proteins (a few nanometers) to that of entire cells (~ 100 microns or more). This highly interdisciplinary work lies at the intersection of engineering, physics, biology and chemistry.

Our primary interest lies in understanding the mechanical properties of the cytoskeleton, a dynamic protein polymer network that forms the foundation of cellular architecture, giving cells strength and enabling them to crawl, change shape and divide. This complex network is comprised of several classes of protein filaments, including actin and microtubules, and is constantly being remodeled through the work of accessory binding proteins that promote changes in filament length and organization. We are particularly interested in the role of motor proteins, enzymes that use the energy released in chemical reactions to exert forces and move in cells.

To investigate the biophysical and biochemical basis of cellular mechanics, we use a wide variety of experimental techniques, including: high-precision optical trapping to probe single molecules of motor and crosslinking proteins; micromechanical manipulation of cytoskeletal networks that are reconstituted from purified components or assembled in cell extracts; and advanced fluorescence imaging of the self-assembly of large protein complexes. We are also working to develop novel methods of measuring interaction and deformation forces within living cells.

Affiliations

• Neuroscience Research Institute
• Center for Stem Cell Biology and Engineering
• California NanoSystems Institute
• Center for BioEngineering
• Materials Research Laboratory

Awards/Honors

• NSF CAREER Award, 2013
• Burroughs Wellcome Career Award at the Scientific Interface, 2005
• Damon Runyon Cancer Research Foundation Postdoctoral Fellowship, 2004

Selected Publications

• Evolute-based Hough transform method for characterization of ellipsoids, Journal of Microscopy, In Press, 2013, Bugra Kaytanli and Megan T. Valentine
• Force spectroscopy of complex biopolymers with heterogeneous elasticity, Soft Matter, 9, 2013, 772-778, David Valdman, Benjamin J. Lopez, Megan T. Valentine, and Paul J. Atzberger, web link
• Mechanical and functional properties of epothilone-stabilized microtubules, Cytoskeleton, In press, 2013, Dezhi Yu, Veronica Pessino, Steve Kuei, and Megan T. Valentine
• Microrheology of highly crosslinked microtubule networks is dominated by force-induced crosslinker unbinding, Soft Matter, 9, 2013, 383-393, Yali Yang, Mo Bai, William S. Klug, Alex J. Levine and Megan T. Valentine, web link
• Direct correlation between creep compliance and deformation in entangled and sparsely crosslinked microtubule networks, Soft Matter, 8, 2012, 1776-1784, Yali Yang, Jun Lin, Bugra Kaytanli, Omar Saleh and Megan T. Valentine, web link
• High-force NdFeB-based magnetic tweezers device optimized for microrheology experiments, Review of Scientific Instruments, 83, 2012, 053905, Jun Lin, Megan T. Valentine, web link
• Ring-shaped NdFeB-based magnetic tweezers enables oscillatory microrheology measurements, Applied Physics Letters, 100, 2012, 201902, Jun Lin, Megan T. Valentine, web link
• Spectral Analysis Methods for the Robust Measurement of the Flexural Rigidity of Biopolymers, Biophysical Journal, 102, 2012, 1144-1153, David Valdman, Paul J. Atzberger, Dezhi Yu, Steve Kuei and Megan T. Valentine, web link
• Portable magnetic tweezers device enables visualization of the three-dimensional microscale deformation of soft biological materials, BioTechniques, 51, 2011, 29-34, Yali Yang, Jun Lin, Ryan Meschewski, Erin Watson, and Megan T. Valentine, web link
• Force and premature binding of ADP can regulate the processivity of individual Eg5 dimers, Biophysical Journal, 97, 2009, 1671-7, Megan T. Valentine and Steven M. Block, web link
• Precision steering of an optical trap by electro-optic deflection, Optics Letters, 33, 2008, 599-601, Megan T. Valentine, Nicholas R. Guydosh, Braulio Gutiérrez-Medina, Adrian N. Fehr, Johan O. Andreasson, and Steven M. Block
• Individual dimers of the mitotic kinesin motor Eg5 step processively and support substantial loads in vitro, Nature Cell Biology, 8, 2006, 470, Megan T. Valentine, Polly M. Fordyce, Troy C. Krzysiak, Susan P. Gilbert, and Steven M. Block
• Mechanical properties of Xenopus egg cytoplasmic extracts, Biophysical Journal, 88, 2005, 680, M.T. Valentine, Z.E. Perlman, T.J. Mitchison, and D.A. Weitz
• Colloid surface chemistry critically affects multiple particle tracking measurements of biomaterials, Biophysical Journal, 86, 2004, 4004-14, M.T. Valentine, Z.E. Perlman, M.L. Gardel, J.H. Shin, P. Matsudaira, T.J. Mitchison, and D.A. Weitz
• Microrheology of entangled F-actin solutions, Physical Review Letters, 91, 2003, 158302, M.L. Gardel, M.T. Valentine, J.C. Crocker, A.R. Bausch, and D.A. Weitz
• Investigating the microenvironments of inhomogeneous soft materials with multiple particle tracking, Physical Review E, 64, 2001, 061506, M.T. Valentine, P.D. Kaplan, D. Thota, J.C. Crocker, T. Gisler, R.K. Prud’homme, M. Beck, and D.A. Weitz
• Microscope-based static light scattering instrument, Optics Letters, 26, 2001, 890, M.T. Valentine, A.K. Popp, P.D. Kaplan, and D.A. Weitz
• Two-point microrheology of inhomogeneous soft materials, Physical Review Letters, 85, 2000, 888, John C. Crocker, M.T. Valentine, Eric R. Weeks, T. Gisler, P.D. Kaplan, A.G. Yodh, and D.A. Weitz
• Forces on a colloidal particle in a polymer solution: a study using optical tweezers, Journal of Physics: Condensed Matter (U.K.)., 8, 1996, 9477, M.T. Valentine, L.E. Dewalt, and H.D. Ou-Yang