Ion channels are instrumental in the generation of membrane potential, receptor potential, and action potential. They are the molecular building blocks for what is an essential characteristic of many cells in neuroscience: excitability. These proteins are implicated in the physiology and pathophysiology of all excitable tissues, underlie many disease processes including epilepsies and arrhythmias, and are major targets of essential drugs used in clinical medicine. Potassium channels are the phylogenetic founders of a large superfamily of structurally related ion channels that includes nucleotide gated channels, sodium channels, and calcium channels. Potassium channels are typically assembled from four identical subunits in a four-fold symmetrical fashion. This rather simple structural blueprint and the substantial practical advantage of only one subunit type have made potassium channels a much studied model system. This proposal explores two aspects of potassium channels: drug binding and voltage- dependence.
In aim 1 we will determine the structural basis of the drug-channel interaction.
In aim 2 we will attempt to describe the voltage-sensing domain of the channel in its native form. We will use a combination of cysteine mutagenesis, biochemistry, electrophysiology, site-directed spin labeling, and X-ray crystallography to study two prokaryotic potassium channels: KcsA and KvAP. The long-term goal of this proposal is to understand functional properties of ion channels at a structural level.

Public Health Relevance

Ion channels are membrane proteins that allow ions to pass from one side of the cell membrane to the other. They are the molecular hardware that generates all electrical signals in the human body. These signals are used to coordinate the beating of the heart and underlie the complex function of the central and peripheral nervous system. When ion channels malfunction, serious maladies ensue, such as heart arrhythmias, epilepsy, and even death. Ion channels are also important drug targets. Drugs effecting ion channels are used every day in clinical medicine and are often implicated in serious drug side effects. Determining the precise structure and mechanism of action of these channels will allow for the development of safer and more effective drugs.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM058568-13
Application #
8197591
Study Section
Biophysics of Neural Systems Study Section (BPNS)
Program Officer
Chin, Jean
Project Start
1999-02-01
Project End
2015-03-31
Budget Start
2011-12-01
Budget End
2013-03-31
Support Year
13
Fiscal Year
2012
Total Cost
$333,720
Indirect Cost
$117,720
Name
Rosalind Franklin University
Department
Biochemistry
Type
Schools of Medicine
DUNS #
069501252
City
North Chicago
State
IL
Country
United States
Zip Code
60064
Lenaeus, Michael J; Burdette, Dylan; Wagner, Tobias et al. (2014) Structures of KcsA in complex with symmetrical quaternary ammonium compounds reveal a hydrophobic binding site. Biochemistry 53:5365-73
Cieslak, John A; Focia, Pamela J; Gross, Adrian (2010) Electron spin-echo envelope modulation (ESEEM) reveals water and phosphate interactions with the KcsA potassium channel. Biochemistry 49:1486-94
Shao, Junlong; Cieslak, John; Gross, Adrian (2009) Generation of a calmodulin-based EPR calcium indicator. Biochemistry 48:639-44
Lenaeus, Michael J; Vamvouka, Magdalini; Focia, Pamela J et al. (2005) Structural basis of TEA blockade in a model potassium channel. Nat Struct Mol Biol 12:454-9
Gross, Adrian; Hubbell, Wayne L (2002) Identification of protein side chains near the membrane-aqueous interface: a site-directed spin labeling study of KcsA. Biochemistry 41:1123-8
le Coutre, J; Whitelegge, J P; Gross, A et al. (2000) Proteomics on full-length membrane proteins using mass spectrometry. Biochemistry 39:4237-42