Featured Research

from universities, journals, and other organizations

Structure Of A Nobel-prize Winning Molecule: Aquaporin

Date:
December 29, 2003
Source:
Public Library Of Science
Summary:
Robert Stroud and colleagues, as reported in this issue of PLoS Biology, have now solved the structure of the water channel from Escherichia coli called aquaporin Z. This channel is especially interesting in that it selectively conducts only water at high rates.

This year, Roderick MacKinnon was recognized for working out the atomic structure of an ion channel and Peter Agre for discovering that a major protein found in red blood cells functions primarily as a water channel. Agre went on to establish the family of related channels, which he named "aquaporins." Solving the structure of these channels provided a platform for exploring the underlying molecular mechanisms that allow the proteins to function as filters and maintain osmotic equilibrium. Robert Stroud and colleagues, as reported in this issue of PLoS Biology, have now solved the structure of the water channel from Escherichia coli called aquaporin Z. This channel is especially interesting in that it selectively conducts only water at high rates.

Related Articles


Aquaporins form a large, diverse family of proteins and have been found in bacteria, plants, and animals. Less than a decade ago, scientists discovered the aquaporin Z gene (aqpZ) in E. coli, pointing to the protein's role in regulating water transport in this prokaryote. The aquaporin Z channel protein in E. coli can accommodate a flow of water at rates six times higher than GlpF (aquaglyceroporin glycerol facilitator, a channel protein that transports both glycerol and water in E. coli) making it the prime subject for studying the selectivity of a high-conducting water channel. And because the two main classes of aquaporins occur in E. coli--which means they're exposed to the same cellular environment--the opportunities for comparative structural and functional analyses, combined with site-directed mutagenesis, promise to provide valuable insights into the molecular underpinnings of the selectivity of functionally different aquaporins.

After producing a recombinant form of AqpZ in E. coli, the proteins were crystallized--capturing five water molecules inside--and then analyzed by state-of-the-art high-resolution X-ray diffraction techniques. The architecture of aquaporin Z is typical of aquaporins, with a spiral of eight oxygens providing water-binding sites inside the channel. The outer membrane and cytoplasmic ends of the channel are wider than the interior, which is long and narrow. This structure demonstrates that aquaporin selectivity arises in part from erecting a physical barrier: small molecules, like water, can easily pass, but larger ones simply can't fit. And the strategic positioning of amino acid residues with hydrophilic or hydrophobic properties along the channel helps police the influx of molecules based on their affinity for water. While it seems two amino acid chains located in the middle of the channel also provide a water-friendly surface, Stroud et al. say they play a more intriguing role. Noting that the water molecules occupy the channel in single file, the scientists explain that such an orientation would normally facilitate the random flow of protons (or hydrogen ions), which would be lethal to the cell. This central amino acid pair, they say, restricts the behavior of water molecules in the center of the channel in such a way that prevents "proton jumping" yet keeps the water flowing. With two structural models of aquaporins down to the atomic level in the same species, scientists can now begin to investigate the molecular mechanisms that facilitate their selectivity. The importance of understanding these widely distributed channel proteins was underscored by the Nobel awards this year.


Story Source:

The above story is based on materials provided by Public Library Of Science. Note: Materials may be edited for content and length.


Cite This Page:

Public Library Of Science. "Structure Of A Nobel-prize Winning Molecule: Aquaporin." ScienceDaily. ScienceDaily, 29 December 2003. <www.sciencedaily.com/releases/2003/12/031222065042.htm>.
Public Library Of Science. (2003, December 29). Structure Of A Nobel-prize Winning Molecule: Aquaporin. ScienceDaily. Retrieved November 28, 2014 from www.sciencedaily.com/releases/2003/12/031222065042.htm
Public Library Of Science. "Structure Of A Nobel-prize Winning Molecule: Aquaporin." ScienceDaily. www.sciencedaily.com/releases/2003/12/031222065042.htm (accessed November 28, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Friday, November 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

NASA's First 3-D Printer In Space Creates Its First Object

NASA's First 3-D Printer In Space Creates Its First Object

Newsy (Nov. 26, 2014) The International Space Station is now using a proof-of-concept 3D printer to test additive printing in a weightless, isolated environment. Video provided by Newsy
Powered by NewsLook.com
Bolivian Recycling Initiative Turns Plastic Waste Into School Furniture

Bolivian Recycling Initiative Turns Plastic Waste Into School Furniture

Reuters - Innovations Video Online (Nov. 26, 2014) Innovative recycling project in La Paz separates city waste and converts plastic garbage into school furniture made from 'plastiwood'. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
Blu-Ray Discs Getting Second Run As Solar Panels

Blu-Ray Discs Getting Second Run As Solar Panels

Newsy (Nov. 26, 2014) Researchers at Northwestern University are repurposing Blu-ray movies for better solar panel technology thanks to the discs' internal structures. Video provided by Newsy
Powered by NewsLook.com
Today's Prostheses Are More Capable Than Ever

Today's Prostheses Are More Capable Than Ever

Newsy (Nov. 26, 2014) Advances in prosthetics are making replacement body parts stronger and more lifelike than they’ve ever been. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins