( A wilting water-starved houseplant and...)Membrane research opens window to benefits for plants, humans

The research, which appeared online this month in advance of regular publication by the journal Nature, involved a tandem of basic-science firsts that offer immediate real world applications, the scientists say.

First, Swedish plant biochemists and crystallographers at Lund University and Chalmers University of Technology, studying membrane proteins of spinach, solved the structure of a water-protein channel -- an aquaporin that opens and closes a gate that regulates water movement in and out of cells.

Not only was the discovery the first for a plant-water channel, it was the first plant-membrane channel for which an atomic resolution structure has been determined. "By recovering an X-ray structure of a plant-membrane channel from over-expression in yeast, this work also lays down key technical foundations for future studies on other plant- and human-membrane proteins," said co-author Richard Neutze of Chalmers University.

Taking that structure, scientists at the University of Illinois at Urbana-Champaign used advanced molecular dynamics simulations to study the mechanics of how such proteins respond to cellular signals such as altering pH (acidity and alkalinity) or phosphorylation, a common cellular chemical process that controls protein activity.

Surprisingly, the simulations clearly showed that specific residues that sit far away from a water pore control the opening of the channel, said biophysics professor Emad Tajkhorshid (pronounced uh-MOD tazh-CORE-shid).

The residues, they found, latch onto an intracellular loop of the protein, blocking the water channel when not phosphorylated. When the residues undergo phosphorylation and become charged, they release the loop, opening the channe
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Source:University of Illinois at Urbana-Champaign