A Pocketful of Uranium: Construction of a Selective Uranium-Binding Protein

Feb 12, 2009

(PhysOrg.com) -- The use of uranium as a nuclear fuel and in weapons increases the risk that people may come into contact with it, and the storage of radioactive uranium waste poses an additional environmental risk. However, radioactivity is not the only problem related to contact with uranium; the toxicity of this metal is generally more dangerous to human health.

Researchers are still looking for simple, effective methods for the sensitive detection and effective treatment of uranium poisoning. Researchers led by Chuan He at the University of Chicago and Argonne National Laboratory (USA) have now developed a protein that binds to uranium selectively and tightly. As reported in the journal Angewandte Chemie, it is based on a bacterial nickel-binding protein.

In oxygen-containing, aqueous environments, uranium normally exists in the form of the uranyl cation (UO22+), a linear molecule made of one uranium atom and two terminal oxygen atoms. The uranyl ion also likes to form coordination complexes. It prefers to surround itself with up to six ligands arranged in a plane around the ion’s “equator”. The research team thus chose to develop a protein that offers the uranyl ion a binding cavity in which it is surrounded by the protein’s side-groups in the manner it prefers.

As a template, the scientists used the protein NikR (nickel-responsive repressor) from E. coli, a regulator that reacts to nickel ions. When NikR is loaded with nickel ions, it binds to a special DNA sequence. This represses transcription of the neighboring genes, which code for proteins involved in nickel uptake. If no nickel is present in the bacteria, NikR does not bind to the DNA.

The nickel ion is located in a binding cavity in which it is surrounded by a square-planar arrangement of binding groups. By using several mutation steps, the researchers generated a new protein that can bind uranium instead of nickel. Only three amino acids had to be changed. In the specially designed cavity, the uranyl group has six binding partners that surround it equatorially. In addition, there are spaces for the two terminal oxygen atoms of uranyl.

This NikR mutant only binds to DNA in the presence of uranyl, not in the presence of nickel or other metal ions. This confirms its selectivity for uranyl and may make it useful for the detection of uranyl and nuclear waste bioremediation. It also represents the first step towards developing potential protein- or peptide-based agents for treatment of uranium poisoning.

More information: Chuan He, University of Chicago, Engineering A Uranyl-Specific Binding Protein from NikR, Angewandte Chemie International Edition, doi: 10.1002/anie.200805262

Provided by Wiley

Explore further: Oat breakfast cereals may contain a common mold-related toxin

add to favorites email to friend print save as pdf

Related Stories

Boy or girl? Lemur scents have the answer

3 hours ago

Dozens of pregnancy myths claim to predict whether a mom-to-be is carrying a boy or a girl. Some say you can tell by the shape of a woman's bump, or whether she craves salty or sweet.

SOHO sees something new near the sun

5 hours ago

An unusual comet skimmed past the sun on Feb 18-21, 2015, as captured by the European Space Agency (ESA) and NASA's Solar and Heliospheric Observatory, or SOHO.

Train car design reduced impact in Southern California crash

5 hours ago

(AP)—After a horrific crash a decade ago that killed 11 people and injured 180 more, Southern California's commuter train network began investing heavily in passenger cars designed to protect passengers from the full force ...

Recommended for you

Researchers bring clean energy a step closer

3 hours ago

For nearly half a century, scientists have been trying to replace precious metal catalysts in fuel cells. Now, for the first time, researchers at Case Western Reserve University have shown that an inexpensive metal-free catalyst ...

The construction of ordered nanostructures from benzene

8 hours ago

A way to link benzene rings together in a highly ordered three-dimensional helical structure using a straightforward polymerization procedure has been discovered by researchers from RIKEN Center for Sustainable ...

Superatomic nickel core and unusual molecular reactivity

8 hours ago

A superatom is a combination of two or more atoms that form a stable structural fragment and possess unique physical and chemical properties. Systems, that contain superatoms, open a number of amazing possibilities ...

Oat breakfast cereals may contain a common mold-related toxin

Feb 25, 2015

Oats are often touted for boosting heart health, but scientists warn that the grain and its products might need closer monitoring for potential mold contamination. They report in ACS' Journal of Agricultural and Food Chemistry that s ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

Soylent
not rated yet Feb 12, 2009
All you have to do to dispose of very mildly radioactive uranium is to convert it into insoluble oxide form and put it back from whence it came.

But why would you ever want to?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.