NEWS OF THE WEEK
CATION COURIER STRUCTURAL BIOLOGY: The last family of ligand-gated ion channels reveals its form
A
N ION CHANNEL found in almost every cell of
NATURE
the human body—where it acts as a gatekeeper for positively charged currents that control everything from taste to pain to inflammation—has finally revealed its three-dimensional X-ray structure. The protein conduit is a LOOKmember of the ALIKE Two P2X family of transmembrane ion channels, ion channels which are inhave different spired to open amino acid by the binding sequences of adenosine but similar triphosphate topology. (ATP), a molOne (gold) is ecule better switched on by known for its ATP binding, role as an enerand the other gy carrier than (purple) by as an ion-chanprotons. nel-opening switch.
REACHING FOR THE SUN Researchers from five countries met at the secularized Seeon monastery, in Germany, to discuss energy. SARAH EV ERTS/C&E N
ACS NEWS: Chemists convene in Germany to stake out the challenges for solar energy research
T
HIRTY CHEMISTS from China, Germany, Japan,
the U.K., and the U.S. met on July 23–25 at a monastery in southern Germany to discuss the current state of solar energy research. They also worked to prioritize scientific challenges that must be met before sunlight can be optimally harnessed as an energy alternative to fossil fuels. The meeting, the Chemical Sciences & Society Symposium (CS3), was organized by chemistry associations, including the American Chemical Society, of the five participant countries. Representatives from research funding agencies from those countries, which paid for the conference, also attended. “Big-time problems—like energy—that involve all of humanity require big-time solutions,” says Luis Echegoyen, director of the Chemistry Division of the WWW.CEN-ONLINE.ORG
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The pharmaceutical industry is trying to develop drugs that interfere with P2X ion channels, and this is the first member of that family to succumb to X-ray crystallography, comments Richard J. Evans, a pharmacologist at the University of Leicester, in England, who studies how P2X channels manipulate blood pressure. Furthermore, P2X channels are the last family of ligandgated ion channels to yield to structural determination, Evans adds. For years, he says, “people have been hoping the high-resolution structure of a P2X channel would come.” After seven years of tinkering with the P2X4 channel, a team of researchers, led by crystallographer Eric Gouaux of the Vollum Institute at Oregon Health & Science University, finally solved the structure of the membrane protein in the closed conformation (Nature 2009, 460, 599). The Gouaux group also reports the 3-D structure of an acid-sensing, proton-gated ion channel and shows that the ATP- and proton-gated ion channels have similar overall architectures, despite the fact that the amino acid sequences of both proteins share almost no similarity (Nature 2009, 460, 592). Both ion channels have an hourglass structure. The two proteins also contain similar “vestibules,” which are interior compartments lined with negatively charged amino acids that likely entice positively charged cations into the pore, Gouaux says. Gouaux hopes the structures will aid the development of new compounds to modulate, inhibit, or activate the channels. Such compounds, he adds, “might prove useful as therapeutic agents.”—SARAH EVERTS
U.S. National Science Foundation. “We wanted to get people together to figure out how to collaborate on an international level” to address the energy challenge. The goal of the symposium was to pinpoint the “steps required and the direction chemistry research needs to take” to enable solar energy to best contribute to the global energy solution, says Julie Callahan, who works in ACS’s Office of International Activities and represented the society at the conference. The three-day event focused on four topics related to solar energy: mimicking photosynthesis using synthetic materials, employing biomass to convert sunlight into usable energy, creating innovative photovoltaics, and storing solar energy in batteries and as fuel. A conference report aimed at the public, politicians, and policymakers is currently in the works. “The meeting was an experiment worth trying,” says Teruto Ohta, executive director of the Chemical Society of Japan. “These are great challenges, and no country alone knows exactly how to handle them.” Organizers hope the conference will be the first of several that tackle “the global challenges of the 21st century and the indispensible role that the chemical sciences play in addressing these issues,” says Klaus Müllen, president of the German Chemistry Association.—SARAH EVERTS
AUGUST 3, 2009
