Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Bacterial protein mimics host to cripple defenses

23.12.2005


Like a wolf in sheep’s clothing, a protein from a disease-causing bacterium slips into plant cells and imitates a key host protein in order to cripple the plant’s defenses. This discovery, reported in this week’s Science Express by researchers at the Boyce Thompson Institute (BTI) for Plant Research, advances the understanding of a disease mechanism common to plants, animals, and people.



That mechanism, called programmed cell death (PCD), causes a cell to commit suicide. PCD helps organisms contain infections, nip potential cancers in the bud, and get rid of old or unneeded cells. However, runaway PCD leads to everything from unseemly spots on tomatoes to Parkinson’s and Alzheimer’s diseases.

BTI Scientist and Cornell University Professor of Plant Pathology Gregory Martin studies the interaction of Pseudomonas syringae bacteria with plants to find what determines whether a host succumbs to disease. Martin and graduate student Robert Abramovitch previously found that AvrPtoB, a protein Pseudomonas injects into plants, disables PCD in a variety of susceptible plants and in yeast (a single-celled ancestor of both plants and animals). Abramovitch and Martin compared AvrPtoB’s amino acid sequence to known proteins in other microbes and in higher organisms, but found no matches that might hint at how the protein works at the molecular level.


"We had some biochemical clues to what AvrPtoB was doing, but getting the three-dimensional crystal structure was really key," Martin explained. To find that structure, Martin and Abramovitch worked with collaborators at Rockefeller University. The structure of AvrPtoB revealed that the protein looks very much like a ubiquitin ligase, an enzyme plant and animal cells use to attach the small protein ubiquitin to unneeded or defective proteins. Other enzymes then chew up and "recycle" the ubiquitin-tagged proteins.

To confirm that AvrPtoB was a molecular mimic, Martin and Abramovitch altered parts of the protein that correspond to crucial sites on ubiquitin ligase. These changes rendered Pseudomonas harmless to susceptible tomato plants, and made the purified protein inactive. AvrPtoB’s function is remarkable not only because its amino acid sequence is so different from other ubiquitin ligases, but also because bacteria don’t use ubiquitin to recycle their own proteins.

"An interesting question is where this protein came from," Martin noted. "Did the bacteria steal it from a host and modify it over time, or did it evolve independently? We don’t know."

Regardless, the discovery "helps us understand how organisms regulate cell death on a fundamental level," Martin said. AvrPtoB provides a sophisticated tool researchers can use to knock out PCD brought on by a variety of conditions, shedding light on immunity. The protein itself or a derivative might one day be applied to control disease in crops or in people. For now, Martin and Abramovitch are working to find which proteins AvrPtoB acts on, and what role those proteins play in host PCD.

Shawna Williams | EurekAlert!
Further information:
http://www.cornell.edu

More articles from Life Sciences:

nachricht Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY

nachricht NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>