Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Molecular Bodyguards for Immature Membrane Proteins


During their formation within the cells, many proteins rely on the assistance of molecular protectors, so-called chaperones. They help the proteins to fold correctly and thus ensure the right final structure. The roles of chaperones in membrane protein folding have long remained unclear. Researchers at the Biozentrum, University of Basel, and at ETH Zurich have now shown how chaperones stabilize an immature bacterial membrane protein and guide it in the right folding direction, thus protecting it from misfolding. Their study was recently published in “Nature Structural & Molecular Biology”.

Cellular machines continuously produce long polypeptide chains, the proteins. In order to properly fulfill its cellular function, a protein must however first adopt its correct spatial structure. In each cell there are molecular helper proteins called chaperones. They take care of the immature proteins to help them in the folding process and thus preventing errors.

Chaperones (light blue) promote the insertion and folding of the bacterial membrane protein FhuA (yellow).

University of Basel, Biozentrum

The scientists led by Prof. Sebastian Hiller from the Biozentrum, University of Basel, and Prof. Daniel Müller from the Department of Biosystems Science and Engineering (D-BSSE), ETH Zurich in Basel have discovered how two chaperones in the gut bacterium E. coli protect the membrane protein FhuA during transport and assist its insertion into the membrane.

Chaperones help insertion of membrane protein

... more about:
»Biozentrum »Bodyguards »ETH »bacteria »proteins »structure

Countless proteins, which transport nutrients and signaling molecules, are embedded in the outer membrane of bacteria. One of these membrane transporters is the protein FhuA. Via this protein, the bacteria take up vitally important iron but also antibiotics. But how does the very large, barrel-shaped FhuA protein reach the outer membrane intact? The scientists from the Biozentrum and the D-BSSE have investigated this process more deeply.

In order to reach its goal in the outer membrane, FhuA uses the help of several chaperones. Using structural analyses and single-molecule force spectroscopy, the researchers have now elucidated how these two chaperones stabilize the immature protein and prevent misfolding. “This process is extremely dynamic,” says Hiller.

“Under the protection of the chaperones, within a millisecond, FhuA constantly changes its structure. It thus explores energetically favorable conformations which enable the stepwise insertion and folding of individual protein segments into the membrane.” With the insertion of the final protein segment, FhuA acquires its mature and functional barrel structure. Left unprotected, FhuA would fold incorrectly and finally aggregate.

Protein chaos without chaperones

Chaperones are significantly involved in the formation of functional proteins. They play an important role in the correct folding of soluble proteins and furthermore are necessary for the insertion of membrane proteins into the bacterial outer membrane. Because several organelles in plant and animal cells are of bacterial origin, chaperones also protect their membrane proteins in a similar manner and assist during membrane insertion. The new findings are consequently of great relevance also for diseases caused by misfolded proteins such as Alzheimer's, Parkinson's or cystic fibrosis.

“It has been known for a long time that chaperones protect other proteins from misfolding and encourage them to fold correctly. Now, our work has succeeded in demonstrating – for the first time in biological membranes – how chaperones support the membrane proteins that are key to pharmaceutical research,” explains ETH Professor Daniel Müller. Until recently, these could almost only be investigated using artificial environments. However, this meant that there was barely any understanding of how proteins fold into a cell’s membrane.

“To give a loose analogy, until now it was like putting a cow on a sheet of ice in order to investigate its natural behaviour and then observing surprising reactions,” says Müller. “We now have a better understanding of how the cell incorporates its molecular machines into membranes so that they can perform their versatile duties.”

Original source

Johannes Thoma, Björn M Burmann, Sebastian Hiller & Daniel J Müller
Impact of holdase chaperones Skp and SurA on the folding of β-barrel outer-membrane proteins
Nature Structural & Molecular Biology (2015), doi: 10.1038/nsmb.3087

Further information

Prof. Sebastian Hiller, University of Basel, Biozentrum, tel. +41 61 267 20 82, email:
Prof. Daniel J. Müller, ETH Zurich, Department of Biosystems Science and Engineering, tel. +41 61 387 33 07, email:

Katrin Bühler | Universität Basel
Further information:

Further reports about: Biozentrum Bodyguards ETH bacteria proteins structure

More articles from Life Sciences:

nachricht First time-lapse footage of cell activity during limb regeneration
25.10.2016 | eLife

nachricht Phenotype at the push of a button
25.10.2016 | Institut für Pflanzenbiochemie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Greater Range and Longer Lifetime

26.10.2016 | Power and Electrical Engineering

VDI presents International Bionic Award of the Schauenburg Foundation

26.10.2016 | Awards Funding

3-D-printed magnets

26.10.2016 | Power and Electrical Engineering

More VideoLinks >>>