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James C. Weisshaar

Website | Awards | Publications

Professor, Born 1952

B.S. 1974, Michigan State University

Ph.D. 1979, University of California - Berkeley

Room: 4211
Phone: 608-262-0266
Email: weisshaa@chem.wisc.edu
Position: Professor

Selected Publications

  • M.C. Konopka, I.A. Shkel, M. T. Record, and J.C. Weisshaar, Two-Domain Cytoplasmic Protein Diffusion in Osmotically Stressed Escherichia coli, submitted March, 2008.

  • T. Liu, E.R. Chapman, and J.C. Weisshaar, Productive Hemifusion Intermediates in Fast Vesicle Fusion Driven by Neuronal SNAREs, Biophys. J. 94, 1303-1314 (2008).

  • M. Konopka, J.C. Weisshaar, and M. T. Record, Methods of Changing Biopolymer Volume Fraction and Cytoplasmic Solute Concentrations for In Vivo Biophysical Studies, Methods in Enzymology, 428, 487-504 (2007).

  • A. Yethiraj and J.C. Weisshaar, Why are lipid rafts not observed in vivo?, Biophys. J., 93, 3113-9 (2007); chosen as "New and Noteworthy".

  • M. Konopka, I. Shkel, S. Cayley, M. T. Record, and J.C. Weisshaar, Crowding and Confinement Effects on Protein Diffusion In Vivo, J. Bacteriology, 188, 6115-6123 (2006).

  • T. Liu, W. Tucker, E.R. Chapman, and J.C. Weisshaar, Fast, SNARE-dependent vesicle fusion in vitro, Biophys. J. 89, 2458-72 (2005); chosen as "New and Noteworthy".

  • M. Konopka and J.C. Weisshaar, Heterogeneous motion of secretory vesicles in the actin cortex of live cells: 3D tracking to 5-nm accuracy, J. Phys. Chem., 108, 9814-9826 (2004)

  • M. Konopka and J.C. Weisshaar, Heterogeneous motion of secretory vesicles in the actin cortex of live cells: 3D tracking to 5-nm accuracy, J. Phys. Chem., 108, 9814-9826 (2004)

Research Description


Quantitative fluorescence microscopy in vivo and in vitro

Principal Investigator: James C. Weisshaar
(608)262-0266, weisshaar@chem.wisc.edu

Graduate Students: Colin Ingram, Tingting Wang, Ben Bratton,
Kem Sochacki, Izzy Smith, Renee Dalrymple,
Somenath Bakshi, Ken Barns

Research Interests: Fluorescence microscopy of biological systems. Design and characterization of a fast, SNARE-driven in vitro single-vesicle fusion assay. PALM imaging of synaptic proteins in live and fixed cells with 5 nm spatial resolution. Diffusion of cytoplasmic and periplasmic proteins in live E. coli under varying conditions of osmotic stress. RNA polymerase motion in live E. coli.

We participate in the revolution in the fluorescence microscopy of biological systems, both in vitro and in live cells. It is increasingly possible to observe the motion of proteins and DNA with single-molecule precision in live cells and in contexts approximating natural conditions. The result is an unprecedented, high resolution view of biological structure and activity. Areas of particular interest include: (1) The structure and function of the proteins responsible for Ca2+-triggered synaptic vesicle fusion, the elementary step in neuron-neuron communication. (2) The diffusive motion of GFP-labeled proteins, including RNA polymerase, in live cells. The cytoplasm is a complex and crowded medium. We know little about how different proteins are transported and carry out their work. Our model system is E. coli, which enables us to build on a tremendous reservoir of knowledge and genetic and pharmacological expertise. (3) Photoactivated localization microscopy (PALM), a new method for locating specific proteins to 5-25 nm resolution in cells. We are interested in the distribution of specific proteins within the E. coli cytoplasm and periplasm and in the stoichiometry and architecture of the proteins at a vesicle fusion site in PC12 cells.





Fig. 1. Schematic of secretory vesicle bound to the plasma membrane by a SNARE complex. Ca2+-triggered alterations in the binding relationships among synaptotagmin and the SNAREs  leads to vesicle fusion.

Figure 2

Fig. 2. Sequential snapshots of an in vitro hemifusion event. Labeled lipids within a single v-SNARE vesicle make two outgoing waves after docking on a t-SNARE-containing bilayer.


Figure 3
Fig. 3. False-color images of GFP within the cytoplasm of a live E. coli cell before, immediately after, and a long time after an intense photobleaching laser pulse. The recovery of the intensity distribution yields an effective proteins diffusion coefficient.

Figure 4

Fig. 4. Images of periplasmic GFP

 

Last Updated: February 4, 2009

 

Awards

  • Hilldale Undergraduate Research Awards, 1993, 1995, 1999, 2001, 2002 (with undergraduates K. Haug , W.-K. Woo, V. Chen, T. Huppert, L. Klein)

  • Fellow, American Physical Society, 2001

  • Wisconsin Alumni Research Foundation Kellett Mid-Career Research Award, 1998-2003

  • Vilas Associate Award, UW-Chemistry, 1997-1998

  • Evan P. Helfaer Professor of Chemistry, 1996-2001

  • Upjohn Award for Teaching Excellence in Chemistry, 1995

  • Hilldale Undergraduate Research Awards, 1993, 1995, 1999, 2001, 2002 (with undergraduates K. Haug , W.-K. Woo, V. Chen, T. Huppert, L. Klein)

  • Romnes Faculty Research Fellowship, UW-Madison, 1991-1996

  • Dreyfus Research Grant for Newly Appointed Faculty in Chemistry, 1981

  • ACS Nobel Laureate Signature Award, 1980
  • NSF Predoctoral Fellow, 1974-77