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.

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 spi
'"/>

Contact: Philip Bernstein
pbernstein@plos.org
415-624-1210
Public Library of Science
22-Dec-2003

Page: 1 2
Related biology news :

1. Structure solved at Scripps shows how one human protein reduces potency of chemotherapy
2. Structure solved by Scripps scientists shows one way that body controls gene expression
3. Structure of HIV-neutralizing antibody solved
4. Structure of key breast cancer receptor determined
5. Structure of cog at the hub of metabolism reveals anti-ageing function
6. Structure of pain-modulating enzyme described by scientists at the Scripps Research Institute
7. Structure reveals details of cells cargo-carriers
8. Structure of key receptor unlocked; Related proteins will fall like dominoes
9. New Science Press launches Proteins: From Sequence to Structure
10. Third piece completes deadly puzzle: Structure of anthrax toxin offers clues to treatment
11. Structure of key protein involved in cancer, osteoporosis and foot-and-mouth disease finally solved