Biology

Edward Moczydlowski
Professor and Chairman
Department of Biology
155 Science Center
Clarkson University
PO Box 5805
Potsdam, NY 13699-5805

E-mail: emoczydl@clarkson.edu
Phone: 315-268-6641
Fax: 315-268-7118

Education
Ph.D., University of California at San Diego - Biology (1980)

Courses taught
BY360 Physiology
BY362 Physiology Laboratory
BY460 Neurobiology
BY476 Current Topics in Biology and Medicine

Research Interests
Neuroscience and membrane biophysics. Structure, function, and pharmacology of ion channel proteins. Use of natural toxins as molecular probes for the study of ion channels and cellular imaging. Saxitoxin and saxiphilin.

Ion Channels and Neurotoxins: Ion channels are integral membrane proteins that mediate electrodiffusive transport of inorganic ions (Na +, K +, Ca 2+, Cl -) across cell membranes. Channel proteins play an especially critical role in the nervous system, which is a complex network of highly specialized cells that communicate by means of electrical and chemical signals. From an engineering standpoint, channels may be thought of as electrochemical nanomachines or molecular circuit elements that initiate pathways of sensory perception, muscle contraction, and hormone secretion, among many other physiological functions. A panoply of channel proteins work in concert to produce action potentials, the bioelectrical signals that travel along nerve fibers and encode information in the brain. As might be anticipated however, these key proteins are susceptible to many different types of natural toxins produced by microorganisms and venomous animals. Our laboratory is interested in the molecular mechanisms of particular channel proteins and an array of neurotoxins as they relate to significant issues of biology, medicine, and the environment.

Large Conductance Calcium-activated Potassium Channels (BK Ca): Opening of the BK Ca channel is activated by binding of Ca 2+ to specific sites on a large intracellular domain. We have shown that a C-terminal fragment of the Drosophila BK Ca channel exhibits 45Ca 2+ binding activity using a protein blot overlay assay. We have also investigated the physical basis of modulation of BK Ca channel conductance by different classes of phospholipids using planar bilayer reconstitution. Recently, we synthesized a novel biotinylated derivative of the scorpion toxin, iberiotoxin, that has high affinity for an extracellular blocking site on the channel. We are applying this toxin derivative to fluoresence imaging of BK Ca channels in living cells.

Structural Role of Inorganic Cations in the Quaternary Structure of the KcsA K + channel: KcsA is a K + channel protein from a bacterium called Streptomyces lividans. Based on work of Rod MacKinnon (Doyle et al., 1998. Science 280: 69-77), a co-recipient of the 2003 Nobel Prize in Chemistry, KscA has a three-dimensional structure that is very similar to human K + channels that mediate vital functions of the nervous system. This channel protein has an exquisite mechanism of ionic selectivity, preferring inorganic cations such as K +, Rb +, and Tl + over slightly smaller ions such as Na + and Li +. We have recently developed a new approach to measuring ion-channel interactions of KcsA based on the use of gel electrophoresis (SDS-PAGE) to monitor the stability of the channel tetramer in the presence of different ions. We are currently using this approach to measure the binding affinity of KscA for different inorganic cations and plan to extend this technique to other types of K + channels.

Saxitoxin (STX) and Saxiphilin: In 1988, our laboratory discovered a novel soluble binding-protein for the neurotoxin, saxitoxin, in plasma of the bullfrog, Rana catesbeiana. STX is small cationic molecule produced by toxic dinoflagellates in the ocean and cyanobacteria in freshwater environments. The frog STX-binding protein (named saxiphilin) is homologous to the transferrin family of Fe 3+-binding proteins that include serum transferrin, lactoferrin, and melanotransferrin. It has since become clear that saxiphilin is just one example of number of transferrin-related proteins that do not bind Fe 3+. However, little is known about the function of such proteins. We are working on improved methods for production of recombinant saxiphilin. Saxiphilin will be used to develop a fluorescence-based assay for saxitoxin, which is the toxic principle of paralytic shellfish poisoning in humans. We also plan to clone related saxiphilin genes from other species and study the biological function of this protein.

Publications (last 5 years)
Bingham, J.-P., Bian, S., Tan, Z.-Y., Takacs, Z., and Moczydlowski, E. "Synthesis of a biotin derivative of iberiotoxin: binding interactions with streptavidin and the BK Ca2+-activated K+ channel expressed in a human cell line." Bioconjugate Chemistry 17: 689-699 2006.

M.N. Krishnan, J.-P. Bingham, S.H. Lee, P. Trombley and E. Moczydlowski, "Functional role and affinity of inorganic cations in stabilizing the tetrameric structure of the KcsA K + channel," J. Gen. Physiol., 126: 271-283 2005.

J-P. Bingham, N.M. Broxton, B.G. Livett, J.G. Down, A. Jones and E.G. Moczydlowski, "Optimizing the connectivity in disulfide-rich peptides:alpha-conotoxin SII as a case study," Anal. Biochem., 338: 48-61 2005.

S.-Y. Wang, J. Mitchell, E. Moczydlowski and G.K. Wang, "Block of Inactivation-deficient Na + Channels by Local Anesthetics in Stably Transfected Mammalian Cells: Evidence for Drug Binding Along the Activation Pathway," J. Gen. Physiol., 124: 691-701 2004.

S.-Y. Wang, E. Moczydlowski and G.K. Wang, "Inactivation-deficient human skeletal muscle Na + channels (hNav1.4-L443C/A444W) in stably transfected HEK293 cells," Receptors and Channels, 10: 131-138 2004.

J.B. Park, H.J. Kim, P.D. Ryu and E. Moczydlowski, "Effect of phosphatidylserine on unitary conductance and Ba 2+ block of the BK Ca 2+-activated K + channel: Re-examination of the surface charge hypothesis," J. Gen. Physiol., 121: 357-397 2003.