Kenneth A. Christensen
Assistant Professor
Analytical Chemistry
Phone: (864) 656.0930
Office: n/a
E-mail: kchris@clemson.edu
Research Interests | Publications
Dr. Christensen earned his B.S. degree in chemistry from Brigham Young University in 1992 and his Ph. D. in analytical chemistry from the University of Michigan in 1997. After graduation, he did postdoctoral work with Prof. Joel Swanson at the University of Michigan Medical School (Department of Microbiology & Immunology). In addition, he worked in Prof. John Collier's lab at Harvard Medical School (Department of Microbiology & Molecular Genetics) before joining the faculty at Clemson University.
Research Interests
A quantitative understanding of the biophysical mechanisms of microbial pathogenesis is required if effective therapeutic countermeasures are to be designed. Hence, investigations of the molecular recognition and host cellular responses to microbial toxin proteins, including potential biowarfare agents, are of fundamental importance. Additionally, since many microbial pathogens or their secreted virulence factors require entry into host cells via an endosomal or phagosomal pathway, a thorough characterization of the dynamics of the intra-endosomal or phagosomal environment is a necessary first step in understanding how pathogens sense and manipulate their surroundings for survival in the host. This lab develops and utilizes optical spectroscopy and time-lapse microscopy as tools to address these and similar fundamental questions in biochemistry, microbiology, and biophysics. Applications of quantitative fluorescence spectroscopy and imaging, including single molecule and fluorescence/Förster resonance energy transfer (FRET) microscopy, will be used to answer questions relating to the function of microbial proteins and their interactions with host cells.
Specific areas of interest include:
1. Determination of the biophysical properties and mechanisms of microbial toxins and how they are trafficked within host cells. Fluorescence spectroscopy and single molecule studies will be used to elucidate a quantitative mechanism of anthrax toxin function. Additional work will utilize quantitative fluorescence microscopy to directly observe the cellular trafficking of the anthrax toxin in live cells.
2. Development of spectroscopic imaging modalities to quantify the dynamic endosomal and phagosomal environments, including the transport of water molecules across membranes and the balance and concentration changes of divalent cations. Using biophysical methods, the proteins required for the endosomal regulation of these species will be identified and studied.
3. Elucidation of the quantitative molecular mechanisms and endosomal function of metal binding proteins produced by microbial pathogens. In particular, the calcium binding protein CBP1 from Histoplasma capsulatum will be characterized using spectroscopy, imaging, and other biophysical methods.
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Publications
Christensen, K., Krantz, B., and Collier, R.J., "Interaction of the 20 kDa and 63 kDa Fragments of Anthrax Protective Antigen: Kinetics and Thermodynamic Studies", In preparation.
Wigelsworth, D., Krantz, B., Christensen, K., Lacy, D.B., Juris, S., and Collier, R.J., "Binding Stoichiometry and Kinetics of the Interaction of a Human Anthrax Toxin Receptor, CMG2, with Protective Antigen", Submitted.
Christensen, K., Hoppe, A. and Swanson, J., Working title: "Imaging Water Transport with a Rapid Raman Imaging Microscope", In preparation.
Hoppe, A., Christensen, K., and Swanson, J.A., "Fluorescence Resonance Energy Transfer-Based Stoichiometry in Living Cells", Biophys. J., 2002, 83, 3652-3664
Christensen, K.A., Myers, J.T., Swanson, J.A., "pH-dependent Regulation of Lysosomal Calcium in Macrophages", J. Cell Sci., 2002, 115, 599-607
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