Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Identifying the Path to Infection

10.11.2004


New protein structure is a first step toward preventing E. coli diseases



Scientists from the U.S. Department of Energy’s Brookhaven National Laboratory and Stony Brook University have determined the two-dimensional crystal structure of a membrane protein involved in the process by which the Escherichia coli (E. coli) bacteria infects a human. This protein structure is a first step to better understanding how an E. coli infection begins, which may lead to information on how to block it.

“E. coli is responsible for urinary tract infections, one of the most prevalent diseases in the U.S.,” said Brookhaven biologist Huilin Li, the lead researcher on the study, described in the November 2, 2004, online edition of the Journal of Molecular Biology. “Between 50 and 80 percent of U.S. women will experience a urinary tract infection at least once during their lifetimes.”


“In the first stage of the infection, E. coli binds tightly to human kidney cells, using an ‘adhesive protein’ secreted by the cells through a membrane protein ‘channel.’ Our structure of this protein channel helps show how secretion occurs, which may eventually lead us to determine how to stop E. coli from attaching to the human cell,” said Li.

The protein channel, known as “PapC,” is a member of the “chaperone/usher” family, channels that not only provide a pathway for certain substances to leave a cell but also participate in preparing the substance for secretion. In this case, PapC gathers the “parts” that make up the adhesive and then guides the assembled adhesive out of the cell.

Li and his colleagues found that PapC consists of two main structural elements, with each part containing one opening, or pore. Each pore is approximately two nanometers (billionths of a meter) in diameter, and the entire structure is 11 nanometers in length and seven nanometers wide.

While this structure might suggest that PapC uses both pores simultaneously, the researchers think that only one of the two pores may be in use at once. However, the twin pore configuration might be necessary to coordinate the assembly and secretion of the adhesive. This is consistent with other membrane proteins that perform similar functions. “Our finding provides new insight into how the adhesive protein is assembled and secreted, but we need to know more about this process,” said Li. “A greater understanding of this will aid in the study and treatment of urinary tract infections and other related diseases.”

To determine the structure, the researchers grew a two-dimensional crystal of PapC – a sheet with a thickness of just one protein. To image individual proteins in the crystal, they used a technique called cryo-electron microscopy. In this method, the crystal is cooled to about minus 300 degrees Fahrenheit using liquid nitrogen and placed in an electron microscope. This device bombards the sample with high-energy electrons, which scatter off the atoms in the crystal. A lens inside the microscope focuses these electrons, forming a high-resolution image, which is recorded using film or a digital camera. The recorded images are analyzed by a computer, yielding the structure of the protein molecule.

This method produced a top-down image of the protein channel from an “untilted” sheet of crystals – that is, the electron beam hit the sheet head-on. To determine the channel’s three-dimensional structure, Li and his group plan to perform additional high-resolution imaging experiments using the same crystal sheet, but tilting it to large angles. This will allow the electrons to scatter off and produce an image of the protein channel’s other sides.

This research is a collaborative effort between researchers in Brookhaven Lab’s Biology Department, Tianbo Liu of Brookhaven’s Physics Department, and David Thanassi, a biologist in Stony Brook University’s Department of Molecular Genetics and Microbiology. The research was funded by a Brookhaven Laboratory Directed Research and Development grant, the National Institutes of Health, and the Office of Biological and Environmental Research within the U.S. Department of Energy’s Office of Science.

Laura Mgrdichian | EurekAlert!
Further information:
http://www.bnl.gov

More articles from Life Sciences:

nachricht Individual Receptors Caught at Work
19.10.2017 | Julius-Maximilians-Universität Würzburg

nachricht Rapid environmental change makes species more vulnerable to extinction
19.10.2017 | Universität Zürich

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Electrode materials from the microwave oven

19.10.2017 | Materials Sciences

New material for digital memories of the future

19.10.2017 | Materials Sciences

Physics boosts artificial intelligence methods

19.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>