Ching Kung, Vilas Professor of Genetics and Molecular Biology
Departments: Genetics and Molecular Biology
Research Areas: Sensory transduction, mechano-senses, ion channels
Lab website: www.molbio.wisc.edu/kung
Address: 321A R.M. Bock Labs, 1525 Linden Drive Madison, WI 53706
Our laboratory studies sensory transductions in microbes. We have pioneered the study of ion channels in Paramecium, yeast, and E. coli. The powerful microbial genetics is used to dissect the basic working of ion channels and to define their physiological roles. We also express animal channels in E.coli, yeast, and Xenopus oocyte toward better understanding.
We found the activity and cloned the gene for a mechanosensitive channel, MscL of E. coli. This channel, homopentameric in crystal, protects the bacteria from lysis upon osmotic downshocks. MscL shows definitively that channels receive forces from the lipid bilayer. This fundamental concept is being extended to eukaryotic channels.
We also study the K+ channels of bacteria and yeasts. Forward and reverse genetics are used to dissect this molecule. Similarly we discovered and continue to study a cation channel of the TRP family on the vacuolar membrane of yeast.
The motile behavior of Parameicum is governed by its excitable membrane. Behavioral mutants were isolated and traced to ion exchangers or channel regulators. Two classes of mutants led to the insight that the universal Ca2+ transducer, calmodulin, is often an ion-channel subunit and has a funtional bipartition. These concepts have now been extended to a large number of animal ion channels.
TRPV4 channel is a key molecular model for animal mechanosensation, but how it is activated has been controversial. We have recently expressed the rat TRPV4 in yeast and in Xenopus oocyte and showed that both the wild-type ad brachyolmia-causing TRPV4 channels respond directly to membrane stretch force.
Forward genetics plays a central role in our studies of microbiol ion channels. We champion the use of "gain-of-function" mutations that yield "loose-cannon" channels is especially powerful.