Breakthrough: structure of membrane protein described by Hebrew University, German researchers

Aug 04, 2005
protein

The structure of the membrane protein NhaA has been revealed by researchers at the Hebrew University of Jerusalem and the Max Planck Institute of Germany. Membrane protein research is at the forefront of modern biological study, with great potential consequences for development of new medicinal treatments and genetic engineering of plants.

Image: Illustration of the membrane protein NhaA. Area outlined by the white dots indicate the funnel of the protein extending into the cell membrane.

The research on NhaA has been carried out by Etana Padan, the Adelina and Massimo DellaPergola Professor of Life Sciences, with Dr. Rimon Avraham, both of the Silberman Institute of Life Sciences at the Hebrew University, and Prof. Hartmut Michel, Nobel prize winner for chemistry in 1988, of the Max Planck for biophysics in Frankfurt, Germany. Their work, described in a recent edition of the journal Nature, was supported by a grant from the German-Israel Binational Science Foundation;

Proteins such as NhaA are found in the membranes of every living cell, from bacteria and up to humans. Until now, the structure of fewer than 50 cell membrane proteins have been discovered, as opposed to 30,000 soluble proteins.

“The location of the proteins in the cell membranes presents tremendous difficulties in research,” said Prof. Padan. “Unlike the majority of those proteins which are soluble in water, the membrane proteins are soluble only in fats or in the presence of detergents.”

The cell membrane is the crossroads of busy, two-way “traffic” through which materials and impulses travel into and out of the cell. The fatty cell membrane is impenetrable to most of these materials and signals; and it is therefore the proteins within the membranes that are responsible for the communication between the cell and its environment. Indeed, more than 60 percent of the medicines in use today are directed at the cell membrane proteins. Since the cell membrane proteins are exposed, in part, to areas extending outside the cells, the medicines are able to reach them without entering the cell itself.

In Prof. Padan’s laboratory, the researchers succeeded in isolating the gene that encodes NhaA in bacteria and in producing a large quantity of the protein in its active state. This achievement paved the way for determining the structure of the protein, providing an essential insight into its mechanism of activity and regulation. NhaA protects the volume of the cell and its internal, normative state in terms of its salinity and acidity.

The deciphering of the NhaA protein’s structure was done utilizing three-dimensional crystals of the protein which diffract x-rays. The work of analyzing the diffraction was done using the powerful electron accelerators in Grenoble, France, and Zurich, Switzerland.

“In this way we were able to reveal the wonderful architecture of the membrane protein, which was unknown before,” said Prof. Padan. “In the center of the protein we found a wide funnel which extends into the cell. The funnel narrows and ends at the point at which it binds with the sodium or the hydrogen deep within the cell membrane. Near that point two chains of the protein unite into a unique structure.”

The researchers believe that this unique structure is the basis for the activity of the protein. The protein operates as a kind of pump, utilizing energy which it receives from processes taking place within the cell. The protein structure thus acts as a kind of molecular motor. This “motor” is connected to the area found at the mouth of the funnel that apparently conveys signals to “modulate” the motor according to the acidity within the cell. The result is that the protein’s activity is controlled in accordance with the needs of the cell in relation to its acidic and basic levels.

Explore further: Research geared to keep women from fleeing IT profession

add to favorites email to friend print save as pdf

Related Stories

How plant cell compartments change with cell growth

5 hours ago

A research team led by Kiminori Toyooka from the RIKEN Center for Sustainable Resource Science has developed a sophisticated microscopy technique that for the first time captures the detailed movement of ...

Some anti-inflammatory drugs affect more than their targets

Aug 21, 2014

Researchers have discovered that three commonly used nonsteroidal anti-inflammatory drugs, or NSAIDs, alter the activity of enzymes within cell membranes. Their finding suggests that, if taken at higher-than-approved ...

Solar fuels as generated by nature

Aug 21, 2014

(Phys.org) —Society's energy supply problems could be solved in the future using a model adopted from nature. During photosynthesis, plants, algae and some species of bacteria produce sugars and other energy-rich ...

Researchers discover new strategy germs use to invade cells

Aug 20, 2014

The hospital germ Pseudomonas aeruginosa wraps itself into the membrane of human cells: A team led by Dr. Thorsten Eierhoff and Junior Professor Dr. Winfried Römer from the Institute of Biology II, members of the Cluster ...

The difficult question of Clostridium difficile

Aug 19, 2014

The bacterium Clostridium difficile causes antibiotic-related diarrhoea and is a growing problem in the hospital environment and elsewhere in the community. Understanding how the microbe colonises the hu ...

Recommended for you

Bronze Age wine cellar found

5 hours ago

A Bronze Age palace excavation reveals an ancient wine cellar, according to a study published August 27, 2014 in the open-access journal PLOS ONE by Andrew Koh from Brandeis University and colleagues.

Orphaned children can do just as well in institutions

5 hours ago

The removal of institutions or group homes will not lead to better child well-being and could even worsen outcomes for some orphaned and separated children, according to new findings from a three-year study across five low- ...

User comments : 0