Navigation Links
Membrane research opens window to benefits for plants, humans

A wilting, water-starved houseplant and flood-covered crops have something in common. That knowledge, gleaned from spinach and researchers on two continents, potentially could open the gate to advances in both plant and human health.

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 l for water to pass through.

The researchers theorize the gating activity is universal in all plant aquaporins, because sequencing has shown the gating loop to be conserved in them.

"Plant cells close their water channels in response to drought stress in order to preserve their water content," said Tajkhorshid, who also is assistant director of research of the Theoretical and Computational Biophysics Group at the U. of I. Beckman Institute for Advanced Science and Technology. "It is interesting that they can also protect themselves against water overflow under flooding conditions by closing the very same water channels. It is amazing that although distinct cellular signals are involved in these two types of closing events, both mechanisms are mediated through the same structural elements of the protein -- that is by plugging the cytoplasmic entrance of the channel with an eolongated intracellular loop."

By atomic scale, the structural difference between open and closed channels is telling. When open, the protein allows water to go through; when closed, its pore size is reduced by 2 angstroms, effectively closing the channel, the Swedish researchers reported.

The work taken together, Tajkhorshid said, is a landmark study in membrane channels. It addresses the mechanism of gating and regulation of plasma membrane proteins in full detail. "We could see how every single atom moves and how collective motions of a large number of atoms resulted in the opening of the channel," he said.

Aquaporins -- discovered in 1991 by Peter Agre, now vice chancellor for science and technology at Duke University Medical Center -- help cells adjust water content. So far 13 forms of aquaporins have been found in animals and another 35 in plants.

Previous work in Tajkorshid's lab has identified how water molecules line up in single file and move as if dancing through open water channels. In less than a second, billions of water molecules can move through a channel.

The growing knowledge of how aquaporins regulate water passage eventually could help agricultural producers boost survivability of drought-stricken and flood-ridden crops. It also could lead to new pharmaceuticals that specifically target these proteins.

"The kidneys are responsible for maintaining a water balance in the body," said Swedish co-author Per Kjellbom in a Lund University news release. "If we can identify a chemical compound that can close the aquaporins in the kidneys, this can be developed into a diuretic drug. By the same token, compounds that stabilize the closed structure could be used in cancer treatment."

Tajkhorshid and Yi Wang, a biophysics graduate student at Illinois, conducted the molecular simulations using VMD and NAMD software developed in their Beckman lab, which is an NIH (National Institutes of Health) Resource for Macromolecular Modeling and Bioinformatics. The simulations were performed at both the National Center for Supercomputing Applications at Illinois and the Pittsburgh Supercomputer Center. Swedish co-authors were Kristina Hedfalk, Urban Johanson, Maria Karlsson, Kjellbom, Neutze and Susanna Tornroth-Horsefield.


Source:University of Illinois at Urbana-Champaign

Related biology news :

1. Columbia research lifts major hurdle to gene therapy for cancer
2. U of M researcher examines newly emerging deadly disease
3. NYU researchers simulate molecular biological clock
4. First atlas of key brain genes could speed research on cancer, neurological diseases
5. New research questions basic tenet of neuron function
6. Vital step in cellular migration described by UCSD medical researchers
7. ASU researchers finds novel chemistry at work to provide parrots vibrant red colors
8. UCSD researchers maintain stem cells without contaminated animal feeder layers
9. Why do insects stop breathing? To avoid damage from too much oxygen, say researchers
10. New protein discovered by Hebrew University researchers
11. First real-time view of developing neurons reveals surprises, say Stanford researchers
Post Your Comments:

(Date:10/6/2015)... , Oct. 6, 2015 Track Group, ... today that it has signed a contract with the ... across the full range of sentences under the Department,s ... of the Americas. "This contract with the Virginia DOC ... the US and advances our position as a trusted ...
(Date:10/5/2015)... ) releases ... (NASDAQ: NXTD ), a biometric authentication company focused ... ) releases the following market and ... a biometric authentication company focused on the growing mobile ... ) releases the following market and ...
(Date:10/1/2015)... Oct. 1, 2015  Biometrics includes diverse set ... body characteristics, such as fingerprints, eye retinas, facial ... of biometrics technology has been constantly increasing in ... five years. In addition to the most prominent ... recognition, other means of biometric authentication are rapidly ...
Breaking Biology News(10 mins):
(Date:10/12/2015)... Oct. 12, 2015 /PRNewswire/ - Aeterna Zentaris Inc. (NASDAQ: ... engaged in developing and commercializing novel treatments in oncology, ... Dennis Turpin , the Company,s former Senior Vice ... its Quebec City office.  ... Chief Executive Officer of the Company commented, "After a ...
(Date:10/12/2015)... October 12, 2015 LabStyle Innovations ... Management Solution, today announced its Medical Director, Dr. ... at MobiHealth,s 5th EAI International Conference on Wireless ... through innovations in mobile and wireless technologies," the conference ... from October 14 - 16, 2015. The conference ...
(Date:10/12/2015)... , Oct. 12, 2015 VolitionRx Limited ... a completed clinical study of its NuQ ® blood-based ... the online issue of Clinical Epigenetics , the official ... conducted in collaboration with Lund University, ... Andersson , MD, PhD, Professor of Surgery and Vice-Dean, Faculty ...
(Date:10/12/2015)... Seattle WA (PRWEB) , ... October 12, 2015 , ... ... for the treatment of retinal diseases that can safely and chronically be administered as ... Global Health Impact Forum co-hosted by The Cleveland Clinic and taking place October 25th ...
Breaking Biology Technology: