Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Structure of RNAi complex now crystal clear

21.06.2012
Researchers at the Whitehead Institute and Memorial Sloan-Kettering Cancer Center have defined and analyzed the crystal structure of a yeast Argonaute protein bound to RNA.

This complex plays a key role in the RNA interference (RNAi) pathway that silences gene expression. Describing the molecular structure of a eukaryotic Argonaute protein has been a goal of the RNAi field for close to a decade.

"You can learn a lot from biochemical experiments, but to more fully understand a protein like Argonaute, it's useful to know where all of the atoms are and which amino acids are playing important roles," says Whitehead Institute Member David Bartel, who is also an MIT professor of biology and a Howard Hughes Medical Institute (HHMI) investigator. "Learning the Argonaute crystal structure is an important step in understanding the RNAi biochemical pathway and will be the basis for many future experiments."

The yeast Argonaute structure is described in the June 21st print issue of Nature.

In humans and most other eukaryotes, the RNAi pathway can reduce cellular protein production by reducing the proteins' RNA templates. By exploiting this pathway, scientists are able to knock down the expression of specific proteins and thereby determine their roles within the cell or organism. The RNAi pathway has also been of considerable interest for the treatment of human disease.

RNAi depends on two proteins, Dicer and Argonaute. Dicer recognizes double-stranded RNA (dsRNA), latches onto it, and chops it into pieces 21-23 nucleotides long. Argonaute recognizes the dsRNA bits, discards one strand, and uses the other as a guide. When a single-stranded RNA matches the guide RNA's sequence, Argonaute cleaves the targeted RNA, thereby preventing it from serving as a template for protein production.

To determine the structure of Argonaute, Bartel and graduate student David Weinberg partnered with Kotaro Nakanishi in Dinshaw Patel's lab at Sloan-Kettering. Although the team expected to solve the structure of Argonaute alone, they were surprised to find that the protein came along with small bits of RNA that were also observed in the structure. The incorporation of these RNAs had switched the protein into an activated state that contained a four-component active site, the identification of which solved a longstanding mystery of what constituted the "missing" fourth component. With the structure of this complex in hand, scientists now have a better understanding for how it works.

"Seeing the crystal structure of a eukaryotic Argonaute for the first time was very exciting—it's such a large protein with a complicated topology and many moving parts," says Weinberg. "It's a really impressive molecular machine."

This work was supported by National Institutes of Health (NIH), the Human Frontier Science Program, the Japan Society for the Promotion of Science, and the National Science Foundation (NSF).

Written by Nicole Giese Rura

David Bartel is a Member at Whitehead Institute for Biomedical Research, where his laboratory is located and all his research is conducted. He is also a Howard Hughes Medical Institute Investigator and a professor of biology at Massachusetts Institute of Technology.

Full Citation:

"Structure of yeast Argonaute with guide RNA"

Nature. June 21, 2012.

Kotaro Nakanishi (1,4), David E. Weinberg (2,3,4), David P. Bartel (2,3) & Dinshaw J. Patel (1).

1. Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
2. Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA
3. Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA

4. These authors contributed equally to this work.

Nicole Giese Rura | EurekAlert!
Further information:
http://www.wi.mit.edu

More articles from Life Sciences:

nachricht Nanoparticle Exposure Can Awaken Dormant Viruses in the Lungs
16.01.2017 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Cholera bacteria infect more effectively with a simple twist of shape
13.01.2017 | Princeton University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

Im Focus: Newly proposed reference datasets improve weather satellite data quality

UMD, NOAA collaboration demonstrates suitability of in-orbit datasets for weather satellite calibration

"Traffic and weather, together on the hour!" blasts your local radio station, while your smartphone knows the weather halfway across the world. A network of...

Im Focus: Repairing defects in fiber-reinforced plastics more efficiently

Fiber-reinforced plastics (FRP) are frequently used in the aeronautic and automobile industry. However, the repair of workpieces made of these composite materials is often less profitable than exchanging the part. In order to increase the lifetime of FRP parts and to make them more eco-efficient, the Laser Zentrum Hannover e.V. (LZH) and the Apodius GmbH want to combine a new measuring device for fiber layer orientation with an innovative laser-based repair process.

Defects in FRP pieces may be production or operation-related. Whether or not repair is cost-effective depends on the geometry of the defective area, the tools...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Multiregional brain on a chip

16.01.2017 | Power and Electrical Engineering

New technology enables 5-D imaging in live animals, humans

16.01.2017 | Information Technology

Researchers develop environmentally friendly soy air filter

16.01.2017 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>