Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Prions act as stepping stones in evolution

16.08.2004


When a protein misfolds, the results can be disastrous. An incorrect change in the molecule’s shape can lead to diseases including Alzheimer’s and Huntington’s. But scientists have discovered that misfolded proteins can have a positive side in yeast, helping cells navigate the dicey current of natural selection by expressing a variety of hidden genetic traits.



What’s more, at the center of this process is a prion, a protein that changes shape in a self-perpetuating way--much like the prion in mammals that is responsible for certain neurological conditions such as Mad Cow disease.

"This is the first time we’ve seen a prion affect a cell in a beneficial way that can determine the evolution of an organism," says Heather True, lead author of the paper, which will appear August 15 in the online edition of the journal Nature.


Previously, True and Whitehead Institute Director Susan Lindquist reported that a particular yeast protein called Sup35 somehow altered the metabolic properties--or phenotype--of the cell when it "misfolded" into a prion state. Sup35 helps guide the process by which cells manufacture protein molecules. However, when Sup35 misfolds into its prion state, it forms amyloid fibers similar to those found in Alzheimer’s patients and causes the cell’s protein-producing machinery to go drastically awry.

More often than not, this is deleterious to the cell. In about 20% of the cases tested, however, the Whitehead team discovered that these new phenotypes afford the yeast cell a survival advantage.

"But we still didn’t know the molecular mechanisms behind this," says True, a former postdoctoral researcher in the Lindquist lab, and now an assistant professor at Washington University, St. Louis. "How exactly did the prion change the appearance of the cell?"

The answer revealed a twist in the traditional understanding of how traits are inherited.

In order for Sup35 to ensure that the cell properly reads the protein recipes contained in genes, it focuses on what are called "stop codons"--sections of DNA that indicate exactly where in the gene a particular protein recipe ends. Sup35 ensures that the cell only translates material prior to these designated codons.

But when it misfolds into a prion conformation, Sup35 gets sloppy, and the cell reads beyond the stop codons, translating genetic information that previously had been dormant. As a result, the cell’s phenotype changes. And here’s where evolution comes in.

On those rare occasions when, due to a particular environment, the altered properties of the cell provide it with a survival advantage, the cell passes that trait on to its progeny. But when the daughter cells are mated and genetic reassortment takes place, they can subsequently pass along this same trait without the prion--that is, the trait becomes fixed in the cell’s lineage and no longer depends on the prion state. "We don’t know yet exactly how the daughter cells do this," says Lindquist, who also is a professor of biology at MIT, "but they do it quickly, often after a single mating."

The prion thus appears to function as an evolutionary stepping stone, affording the population of cells a chance to survive in a new environment where they need a different phenotype until they can acquire the genetic changes that produce the same effect.

These new traits are genetically complex. When Sup35 misfolds into a prion form, it affects a number of genes in one fell swoop.

"This prion," explains Lindquist, "has a capacity to hide and release genetic information throughout the entire genome that can contribute to new traits in a complex way."

David Cameron | EurekAlert!
Further information:
http://www.wi.mit.edu

More articles from Life Sciences:

nachricht Research team creates new possibilities for medicine and materials sciences
22.01.2018 | Humboldt-Universität zu Berlin

nachricht Saarland University bioinformaticians compute gene sequences inherited from each parent
22.01.2018 | Universität des Saarlandes

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Artificial agent designs quantum experiments

On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.

We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Thanks for the memory: NIST takes a deep look at memristors

22.01.2018 | Materials Sciences

Radioactivity from oil and gas wastewater persists in Pennsylvania stream sediments

22.01.2018 | Earth Sciences

Saarland University bioinformaticians compute gene sequences inherited from each parent

22.01.2018 | Life Sciences

VideoLinks Wissenschaft & Forschung
Overview of more VideoLinks >>>