Featured Research

from universities, journals, and other organizations

Protein folding via charge zippers

Date:
January 18, 2013
Source:
Karlsruhe Institute of Technology
Summary:
Membrane proteins are the “molecular machines” in biological cell envelopes. They control diverse processes, such as the transport of molecules across the lipid membrane, signal transduction, and photosynthesis. Their shape, i.e. folding of the molecules, plays a decisive role in the formation of, e.g., pores in the cell membrane. Scientists are now reporting a novel charge zipper principle used by proteins to form functional units.

Like the teeth of a zipper, the charged amino acids (red, blue) form connections between protein segments. In this way, they can form pores in the cell membrane.
Credit: Figure: KIT

Membrane proteins are the "molecular machines" in biological cell envelopes. They control diverse processes, such as the transport of molecules across the lipid membrane, signal transduction, and photosynthesis. Their shape, i.e. folding of the molecules, plays a decisive role in the formation of, e.g., pores in the cell membrane. In the journal Cell, researchers of Karlsruhe Institute of Technology and the University of Cagliari are now reporting a novel charge zipper principle used by proteins to form functional units.

"It is fascinating to see the elegant basic principles that are used by nature to construct molecular assemblies," explains Anne Ulrich, Director of the KIT Institute for Biological Interfaces. "A charge zipper between the charged side chains is an entirely unexpected mechanism used by membrane proteins to neutralize their charges such that they can be immersed into hydrophobic cell membranes."

In the study published now, Ulrich and her team investigate the so-called Twin-arginine translocase (Tat) that is used in the cell membrane of bacteria as an export machinery for folded proteins. Several TatA subunits assemble as a pore that can adapt its diameter to the size of the cargo to be transported. "But how can such a pore be built up from TatA proteins? How can they reversibly form a huge hole in the membrane for a variety of molecules to pass through, but without causing leakage of the cell?," Ulrich formulates the questions studied.

To answer these questions, the researchers studied the molecular structure of TatA protein from the bacterium B. subtilis, which consists of a chain of 70 amino acids. The analysis showed that it folds into a rather rigid, rod-shaped helix that is followed by a flexible, extended stretch. Many amino acids in the helix and the adjacent stretch carry positive or negative charges. Surprisingly, the sequence of charges on the helix is complementary to those in the adjacent stretch of the protein. When the protein is folded up at the connection point like a pocket knife, positive and negative charges will always meet and attract each other. Hence, the protein links up both of its segments, similar to the interlocking teeth of a zipper.

"The clou is that this binding principle also works with the neighboring proteins," Ulrich says. Instead of folding up alone, every TatA protein also forms charge zippers with both of its neighbors. Computer simulations showed that this leads to stable and, at the same time, flexible connections between the adjacent molecules. In this way, any number of proteins can be linked together to form an uncharged ring, which thus lines the TatA pore in the hydrophobic membrane. This novel charge zipper principle does not only seem to play a role in protein transport, but also in the attack of certain antimicrobial peptides on bacteria, or in their formation of biofilms as a response to stress.


Story Source:

The above story is based on materials provided by Karlsruhe Institute of Technology. Note: Materials may be edited for content and length.


Journal Reference:

  1. TorstenH. Walther, Christina Gottselig, StephanL. Grage, Moritz Wolf, AttilioV. Vargiu, MarcoJ. Klein, Stefanie Vollmer, Sebastian Prock, Mareike Hartmann, Sergiy Afonin, Eva Stockwald, Hartmut Heinzmann, OlgaV. Nolandt, Wolfgang Wenzel, Paolo Ruggerone, AnneS. Ulrich. Folding and Self-Assembly of the TatA Translocation Pore Based on a Charge Zipper Mechanism. Cell, 2013; 152 (1-2): 316 DOI: 10.1016/j.cell.2012.12.017

Cite This Page:

Karlsruhe Institute of Technology. "Protein folding via charge zippers." ScienceDaily. ScienceDaily, 18 January 2013. <www.sciencedaily.com/releases/2013/01/130118111559.htm>.
Karlsruhe Institute of Technology. (2013, January 18). Protein folding via charge zippers. ScienceDaily. Retrieved April 17, 2014 from www.sciencedaily.com/releases/2013/01/130118111559.htm
Karlsruhe Institute of Technology. "Protein folding via charge zippers." ScienceDaily. www.sciencedaily.com/releases/2013/01/130118111559.htm (accessed April 17, 2014).

Share This



More Plants & Animals News

Thursday, April 17, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

The Great British Farmland Boom

The Great British Farmland Boom

Reuters - Business Video Online (Apr. 17, 2014) Britain's troubled Co-operative Group is preparing to cash in on nearly 18,000 acres of farmland in one of the biggest UK land sales in decades. As Ivor Bennett reports, the market timing couldn't be better, with farmland prices soaring over 270 percent in the last 10 years. Video provided by Reuters
Powered by NewsLook.com
Flamingo Frenzy Ahead of Zoo Construction

Flamingo Frenzy Ahead of Zoo Construction

AP (Apr. 17, 2014) With plenty of honking, flapping, and fluttering, more than three dozen Caribbean flamingos at Zoo Miami were rounded up today as the iconic exhibit was closed for renovations. (April 17) Video provided by AP
Powered by NewsLook.com
Change of Diet Helps Crocodile Business

Change of Diet Helps Crocodile Business

Reuters - Business Video Online (Apr. 16, 2014) Crocodile farming has been a challenge in Zimbabwe in recent years do the economic collapse and the financial crisis. But as Ciara Sutton reports one of Europe's biggest suppliers of skins to the luxury market has come up with an unusual survival strategy - vegetarian food. Video provided by Reuters
Powered by NewsLook.com
Could Even Casual Marijuana Use Alter Your Brain?

Could Even Casual Marijuana Use Alter Your Brain?

Newsy (Apr. 16, 2014) A new study conducted by researchers at Northwestern and Harvard suggests even casual marijuana use can alter your brain. 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:
from the past week

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