Navigation Links
Researchers identify proteins making up mechanosensitive ion channels
Date:6/2/2008

Researchers at Washington University in St. Louis are the first to identify two proteins responsible for mechanosensitive ion channel activities in plant roots. Scientists have long known that plant cells respond to physical forces. Until now, however, the proteins controlling the ion channel response remained a mystery.

As the name suggests, mechanosensitive channels are paths through the cell membrane that respond to mechanical forces such as gravity, pressure, or touch. Under certain forces, a channel opens, allowing the flow of ions, such as calcium and potassium ions, into and out of the cell. Different forces might close the channel, stopping the flow.

This cross-membrane ion flow has been measured electrophysically, using a technique called the patch-clamp method. But the molecular nature of the channels themselves was not known. Now, knowing the proteins involved makes it possible to discover what the channels do for the whole plant.

"People have been characterizing mechanosensitive channels in plants for 20 years," said Elizabeth Haswell, Ph.D., assistant professor of biology at Washington University in St. Louis and lead investigator of this project, "This is the first time anybody has been able to show which proteins underlie these activities."

Plants do it, bacteria do it

The two proteins governing ion channels in Arabidopsis root are MSL9 and MSL10, according to the study published in the May 20 issue of Current Biology. MSL stands for MscS-Like proteins because of their similarity to a family of bacterial channels known as MscS (mechanosensitive channels of small conductance). Even though bacteria and plants are not closely related in terms of evolution, this study shows that bacterial and plant cells are probably using the same types of proteins to respond to mechanical forces.

To establish that the channels were in fact mechanosensitive, Haswell's French colleagues used the patch-clamp method to measure the movement of ions across the membrane of Arabidopsis root cells as the pressure inside the cell increased. These experiments demonstrated that increasing cellular pressure also increased the ion flow across the membrane. Likewise, as the pressure inside the cell went down, the ion flow decreased.

To determine whether MSL9 and MSL10 were responsible for this ion flow, Haswell created a mutant line of Arabidopsis without either type of protein. When the root cells of the plants lacking MSL9 and MSL10 were tested, the researchers saw very little change in ion flow across the membrane as the pressure inside the cell increased. In other words, without these two proteins, very little channel activity was seen. And the little channel activity they did measure was shown to be caused by different proteins.

Two to tango

Having shown that MSL9 and MSL10 were responsible for the ion channel activity, Haswell and colleagues set out to determine if both were required for the response or if only one did most of the work. Therefore, they tested plants that lacked only one of each protein and were surprised to discover that cells with only MSL9 showed one type of activity and cells with only MSL10 showed a different type of activity. And, importantly, cells with both proteins showed a third type, suggesting that both MSL9 and MSL10 are required to produce the mechanosensitive channel activity seen in wild-type Arabidopsis root.

Haswell and colleagues propose that the channel is composed of subunits of both proteins MSL9 and MSL10 and that this combined structure results in the unique mechanosensitive ion channel behavior observed in the wild-type plants and not in any of the mutant lines.

Despite identifying proteins that govern this ion channel response in Arabidopsis root, mysteries remain. To determine how the mutant plants might be defective and reveal the purpose of the channels, Haswell's group grew the plants that lacked these channels under challenging conditions, including high salt, root barriers, and dehydration. "We tried hundreds of experiments, but we never saw a difference between the mutant and wild-type," said Haswell, "but that's definitely one of the next big steps to find out what the channels really do and why they're important."


'/>"/>

Contact: Elizabeth Haswell
ehaswell@wustl.edu
314-935-9223
Washington University in St. Louis
Source:Eurekalert

Related medicine news :

1. Stanford researchers find culprit in aging muscles that heal poorly
2. UCLA researchers identify markers that may predict diabetes in still-healthy people
3. Mayo Clinic researchers discover new diagnostic test for detecting infection in prosthetic joints
4. Bipolar disorder relapses halved by Melbourne researchers
5. Cell that triggers symptoms in allergy attacks can also limit damage, Stanford researchers find
6. High and mighty: first common height gene identified by researchers behind obesity gene finding
7. Researchers estimate about 9 percent of US children age 8 to 15 meet criteria for having ADHD
8. Majority of 2.4 Million U.S. Children With ADHD Not Diagnosed or Consistently Treated, According to New Gold Standard Study by Cincinnati Childrens Researchers
9. Researchers develop long-lasting growth hormone
10. Jefferson immunology researchers halt lethal rabies infection in brain
11. Purdue researchers develop technology to detect cancer by scanning surface veins
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:2/8/2016)... (PRWEB) , ... February 08, 2016 , ... Coast Dental ... February is National Children’s Dental Health Month and family dentist Yvonne Dorrian, DMD, is ... at Coast Dental , located next to Target at 1207 North Peachtree Parkway ...
(Date:2/8/2016)... New York, NY (PRWEB) , ... February 08, 2016 , ... ... handles are too much to handle, you are not alone. According to the Center ... conditions include heart disease, stroke, type 2 diabetes and certain types of cancer, some ...
(Date:2/8/2016)... ... 2016 , ... Delta Dental of California and its affiliated companies announced today ... Radine, who recently retired as president and CEO of Delta Dental of California and ... the Year , helped lead the effort to raise funds for studies to strengthen ...
(Date:2/8/2016)... ... February 08, 2016 , ... Discover the Rocky Mountain ... 1,400 booths and 700 companies. Attendees also get to see the most incredible ... Garden & Home Show , at the Colorado Convention Center - 700 14th St. ...
(Date:2/8/2016)... ... February 08, 2016 , ... Guruji Mahendra Kumar Trivedi is offering ... 2016 in honor of his birthday on February 10th. During this time, people ... is known by over 250,000 people from over 40 different countries as an “ordinary ...
Breaking Medicine News(10 mins):
(Date:2/8/2016)... , Feb. 8, 2016  Echo ... medical device company focused on non-invasive continuous ... announced today announced that it will host ... February 17, 2015 at 9:00 a.m. Eastern ... discuss its corporate strategy, advancements in its ...
(Date:2/8/2016)... Feb. 8, 2016 Nueterra, the ... specialized in the development of equity partnerships ... it has divided its interests between two ... Capital will continue the founding company,s private ... operate a national system of integrated provider ...
(Date:2/8/2016)... Intarcia Therapeutics, Inc. today announced the appointment of ... created role of Vice President, Head of Global Medical ... of leadership experience at leading pharmaceutical, biotechnology, and health ... Most recently Dr. Yee served as VP, Head of ... Officer at AstraZeneca, where he led medical affairs across ...
Breaking Medicine Technology: