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 Seeing on the Quick: New Insights into Active Vision in the Brain
15.08.2018 | Eberhard Karls Universität Tübingen

nachricht New Approach to Treating Chronic Itch
15.08.2018 | 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: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

Im Focus: Lining up surprising behaviors of superconductor with one of the world's strongest magnets

Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur

What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...

Im Focus: World record: Fastest 3-D tomographic images at BESSY II

The quality of materials often depends on the manufacturing process. In casting and welding, for example, the rate at which melts solidify and the resulting microstructure of the alloy is important. With metallic foams as well, it depends on exactly how the foaming process takes place. To understand these processes fully requires fast sensing capability. The fastest 3D tomographic images to date have now been achieved at the BESSY II X-ray source operated by the Helmholtz-Zentrum Berlin.

Dr. Francisco Garcia-Moreno and his team have designed a turntable that rotates ultra-stably about its axis at a constant rotational speed. This really depends...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

2018 Work Research Conference

25.07.2018 | Event News

 
Latest News

Early opaque universe linked to galaxy scarcity

15.08.2018 | Physics and Astronomy

Molecular switch detects metals in the environment

15.08.2018 | Materials Sciences

Seeing on the Quick: New Insights into Active Vision in the Brain

15.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>