Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

One protein, two channels: Scientists explain mechanism in aquaporins

26.09.2006
Using computer simulations and experimental results, researchers at the University of Illinois at Urbana-Champaign and the University of Arizona have identified a key component of the gating mechanism in aquaporins that controls both the passage of water and the conduction of ions.

Aquaporins are a class of proteins that form membrane channels in cell walls and allow for water movement between a cell and its surroundings. A number of aquaporins, including aquaporin-1, have been found to function as ion channels, as well.

"Understanding the molecular mechanism behind gating in membrane channels could lead to more effective protein engineering," said Emad Tajkhorshid, a professor of biochemistry at Illinois and a researcher at the Beckman Institute for Advanced Science and Technology.

In work funded by the National Institutes of Health, Tajkhorshid and co-workers show that the same protein can be used as a water channel or an ion channel depending on the signaling pathway activated in the cell. The scientists report their findings in the September issue of the journal Structure. Taking advantage of the known crystal structure of aquaporin-1 and the power of molecular dynamics simulations, the researchers explored the central pore as a candidate pathway for conducting ions. Gating of the central pore is controlled by cyclic guanosine monophosphate, a signaling nucleotide inside the cell, which induces a conformational change in one of the aquaporin loops (loop D).

... more about:
»Ion »Pore »Protein »Tajkhorshid »loop

"This loop is very flexible, has four positively charged arginine residues in a row, and extends into the central pore," Tajkhorshid said. "We believe the cGMP interacts with loop D, facilitating its outward motion, which triggers the opening of the gate."

The work highlights a close interaction between simulation and experiment. Based on their simulation results, the researchers designed a mutant in which two arginines in loop D were replaced by two alanines. In laboratory experiments performed at Arizona, the substitution caused an almost complete removal of ion conduction, but had no appreciable effect on water passage.

"Knowing the mechanism gives us a new handle to control the opening or closing of the central pore," Tajkhorshid said. "By modifying the pore-lining residue, or altering the length of loop D that gates the pore, we can shut down the ion conductivity completely, or engineer new aquaporins that can be opened more easily or have a higher ion conduction rate once open."

James E. Kloeppel | EurekAlert!
Further information:
http://www.uiuc.edu

Further reports about: Ion Pore Protein Tajkhorshid loop

More articles from Life Sciences:

nachricht One step closer to reality
20.04.2018 | Max-Planck-Institut für Entwicklungsbiologie

nachricht The dark side of cichlid fish: from cannibal to caregiver
20.04.2018 | Veterinärmedizinische Universität Wien

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

Im Focus: Basel researchers succeed in cultivating cartilage from stem cells

Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.

Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...

Im Focus: Like a wedge in a hinge

Researchers lay groundwork to tailor drugs for new targets in cancer therapy

In the fight against cancer, scientists are developing new drugs to hit tumor cells at so far unused weak points. Such a “sore spot” is the protein complex...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Magnetic nano-imaging on a table top

20.04.2018 | Physics and Astronomy

Start of work for the world's largest electric truck

20.04.2018 | Interdisciplinary Research

Atoms may hum a tune from grand cosmic symphony

20.04.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>