Advertisement

If you have an ACS member number, please enter it here so we can link this account to your membership. (optional)

ACS values your privacy. By submitting your information, you are gaining access to C&EN and subscribing to our weekly newsletter. We use the information you provide to make your reading experience better, and we will never sell your data to third party members.

ENJOY UNLIMITED ACCES TO C&EN

Business

Camera Iris Mechanism Saves Bacteria

Complementary approaches capture ion channel in its open form

by Carmen Drahl
August 28, 2008

Credit: Courtesy of James H. Naismith

Bacteria experience massive pressures against their membranes when they're suddenly exposed to fresh water, but they survive because they possess pressure-relieving protein floodgates in the form of ion channels. Now, two independent research teams propose that one such molecular safety valve works like a camera's iris.

Credit: Courtesy of James H. Naismith
[+]Enlarge
Credit: Courtesy of James Naismith
MscS ion channel widens like a camera???s iris to relieve membrane pressure.
Credit: Courtesy of James Naismith
MscS ion channel widens like a camera???s iris to relieve membrane pressure.

Structural data for the closed form of MscS, a bacterial ion channel that opens in response to increases in membrane tension, already exist. However, trapping MscS in its open form has proven to be a challenge. In one study, led by Eduardo Perozo of the University of Chicago, researchers used cone-shaped lipids to alter the pressure on membrane-embedded MscS and open it (Science 2008, 321, 1210). They characterized the channel with electron paramagnetic resonance spectroscopy.

Meanwhile, James H. Naismith of the University of St. Andrews and Ian R. Booth of the University of Aberdeen, both in Scotland, led a team that crystallized a mutant MscS that is stuck in the open state and determined its X-ray structure (Science 2008, 321, 1179). Both teams suggest that the irislike motion removes a hydrophobic seal from the channel pore, thereby allowing water and ions through.

Article:

This article has been sent to the following recipient:

0 /1 FREE ARTICLES LEFT THIS MONTH Remaining
Chemistry matters. Join us to get the news you need.