Scientists have gotten their first detailed look at the molecular structure of an enzyme that Nature has been using for eons to help silence unwanted genetic messages. A team of researchers with Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California at Berkeley used x-ray crystallography at Berkeley Lab’s Advanced Light Source (ALS) to determine the crystal structure of Dicer, an enzyme that plays a critical role in the process known as RNA interference. The Dicer enzyme is able to snip a double-stranded form of RNA into segments that can attach themselves to genes and block their activity.
A front-on view of a ribbon representation of Dicer shows the enzyme to resemble an axe with the RNA clamp at the handle (the PAZ domain) and the cleaver at the blade (RNase IIIa and IIIb). A flat connector area measuring 65 angstroms is the ruler portion that is used to measure out segments of 25 nucleotides (bases) in length. A segment of double-stranded RNA (blue) is shown passing through the Dicer enzyme.
“With this crystal structure, we’ve learned that Dicer serves as a molecular ruler, with a clamp at one end and a cleaver at the other end a set distance away, that produces RNA fragments of an ideal size for gene-silencing,” said Jennifer Doudna, a biochemist who led this study. Doudna, a leading authority on RNA molecular structures, holds joint appointments with Berkeley Lab’s Physical Biosciences Division, UC Berkeley’s Department of Molecular and Cell Biology and Department of Chemistry. She’s also an investigator with the Howard Hughes Medical Institute (HHMI).
“Knowing the structure of Dicer sets the stage for understanding how Dicer enzymes are involved in other phases of the RNA interference pathway,” Doudna said. “In human cells, the evidence points to Dicer being part of a larger molecular complex that directs the RNA interference process. The core structure of Dicer has been highly conserved by evolution and could serve as a guide in redesigning the RNA molecules that direct specific gene-silencing pathways.”
Lynn Yarris | EurekAlert!
A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
On the way to developing a new active ingredient against chronic infections
21.08.2017 | Deutsches Zentrum für Infektionsforschung
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
21.08.2017 | Materials Sciences
21.08.2017 | Health and Medicine
21.08.2017 | Materials Sciences