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 Researchers uncover protein-based “cancer signature”
05.12.2016 | Universität Basel

nachricht The Nagoya Protocol Creates Disadvantages for Many Countries when Applied to Microorganisms
05.12.2016 | Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

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

14.10.2016 | Event News

 
Latest News

NASA's AIM observes early noctilucent ice clouds over Antarctica

05.12.2016 | Earth Sciences

Shape matters when light meets atom

05.12.2016 | Physics and Astronomy

Researchers uncover protein-based “cancer signature”

05.12.2016 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>