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 New risk factors for anxiety disorders
24.02.2017 | Julius-Maximilians-Universität Würzburg

nachricht Stingless bees have their nests protected by soldiers
24.02.2017 | Johannes Gutenberg-Universität Mainz

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>