Rectification of voltage-gated plant K+ channels

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The family of voltage-gated K+ channels in plants plays an important role in the uptake of potassium from the soil and its distribution throughout the plant. Interestingly, members of this family are structurally very similar but functionally they segregate into inward-rectifying (Kin) channels that allow plant cells to accumulate K+ and outward-rectifying (Kout) channels that mediate K+ efflux. The reason for this divergence is unknown. We generated a synthetic Kin channel (SKIN) and a synthetic Kout channel (SKOUT) that share a high rate of identity (82.5% at the protein level, 90% at the DNA level). The design of the synthetic SKIN and SKOUT clones allowed us further to generate a cDNA library with >30.000.000 different SKIN/SKOUT chimeras. This library will be used to identify chimeras that are inward- or outward-rectifying in order to further increase the degree of identity between these two channel types. The experimental work is accompanied by in silico molecular modeling and dynamics simulations. This combined approach is novel and will allow detailed structural and functional insights into the regulation of plant K+ channels. Furthermore, it will provide informative data for the attempt to design membrane proteins with defined features at the computer.