Nav: Home

Microbial soil cleanup at Fukushima

March 10, 2015

Proteins from salt-loving, halophilic, microbes could be the key to cleaning up leaked radioactive strontium and caesium ions from the Fukushima Dai-ichi Nuclear Power Plant incident in Japan. The publication of the X-ray structure of a beta-lactamase enzyme from one such microbe, the halophile Chromohalobacter sp. 560, reveals it to have highly selective cesium binding sites.

A collaboration between researchers at the Japan Atomic Energy Agency in Tokai, Ibaraki, Kyushu Synchrotron Light Research Center in Saga, Kagoshima University, and Florida State University, Tallahassee, USA, has led to a 1.8 to 2.9 angstrom resolution structure for this enzyme. Anomalous X-ray diffraction also revealed binding sites in the protein for Sr2+ and Cs+ ions, the team reports [Arai et al. (2015).Acta Cryst. D71, 541-554; DOI: 10.1107/S1399004714027734].

The team demonstrated how they could locate caesium ions in a specific site within the protein even in the presence of a nine-fold molar excess of sodium ions, which would normally out-compete any binding site. Intriguingly, the presence of strontium and caesium ions does not diminish the activity of the enzyme determined using isothermal titration calorimetry. "The observation of a selective and high-affinity caesium-binding site provides important information that is useful for the design of artificial caesium-binding sites that may be useful in the bioremediation of radioactive isotopes," the team explains.

It is well known that proteins from halophilic bacteria have an abundance of acidic amino acids and so present an acidic surface that can interact with a range of metal ions. There are twelve types of such enzymes recorded in the Protein Data Bank that can bind to sodium, magnesium, potassium, calcium, iron, zinc, strontium and cadmium ions. Indeed, the presence of these materials in various enzymes is usually a prerequisite for their structure and functionality. Because of this metal affinity, the team reasoned that proteins from halophiles might be useful as molecular mops for separating precious metals from mixtures or in remediation when toxic metals ions must be extracted selectively from a site. More specifically, the proteins could act as models for artificial reagents to be used in this context.

With respect to the Fukushima incident, the team explains that most of the radioactive caesium was deposited on the land at the site. Amounting to 2.4 petabequerels (PBq) of radioactivity and it is fixed in soil particles, comprising weathered biotite, a micaceous mineral found in many igneous and metamorphic rocks. Much of the soil has been removed, but the issue of extracting the radioactive elements for safe disposal has not been addressed. Moreover, the soil that remains at the site is also contaminated and no cost-effective method for extracting the caesium that leeches from it into the environment has been demonstrated.

The team suggests that protein absorbents related to the beta-lactamase from Chromohalobacter might be designed using the techniques of synthetic biology, the most likely approach being to engineer a native protein to make the affinity site described by the team. The genes for such an agent might then be engineered into new breeds of plant that could be grown on the site. With the protein absorbents expressed in plant roots, caesium could be extracted from the soil efficiently, the plants harvested and their new radioactive cargo disposed of safely, leaving behind improved soil.

"Although the removal of caesium is an important theme for us, public acceptance for the use of genetically engineered plants is not strong enough here in Japan, so we are going to shift our theme for finding useful sites to gather other rare materials using engineered proteins derived from the structural information of the halophilic proteins," team member Ryota Kuroki revealed to us.
-end-


International Union of Crystallography

Related Proteins Articles:

New method to monitor Alzheimer's proteins
IBS-CINAP research team has reported a new method to identify the aggregation state of amyloid beta (Aβ) proteins in solution.
Composing new proteins with artificial intelligence
Scientists have long studied how to improve proteins or design new ones.
Hero proteins are here to save other proteins
Researchers at the University of Tokyo have discovered a new group of proteins, remarkable for their unusual shape and abilities to protect against protein clumps associated with neurodegenerative diseases in lab experiments.
Designer proteins
David Baker, Professor of Biochemistry at the University of Washington to speak at the AAAS 2020 session, 'Synthetic Biology: Digital Design of Living Systems.' Prof.
Gone fishin' -- for proteins
Casting lines into human cells to snag proteins, a team of Montreal researchers has solved a 20-year-old mystery of cell biology.
Coupled proteins
Researchers from Heidelberg University and Sendai University in Japan used new biotechnological methods to study how human cells react to and further process external signals.
Understanding the power of honey through its proteins
Honey is a culinary staple that can be found in kitchens around the world.
How proteins become embedded in a cell membrane
Many proteins with important biological functions are embedded in a biomembrane in the cells of humans and other living organisms.
Finding the proteins that unpack DNA
A new method allows researchers to systematically identify specialized proteins called 'nuclesome displacing factors' that unpack DNA inside the nucleus of a cell, making the usually dense DNA more accessible for gene expression and other functions.
A brewer's tale of proteins and beer
The transformation of barley grains into beer is an old story, typically starring water, yeast and hops.
More Proteins News and Proteins Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Climate Mindset
In the past few months, human beings have come together to fight a global threat. This hour, TED speakers explore how our response can be the catalyst to fight another global crisis: climate change. Guests include political strategist Tom Rivett-Carnac, diplomat Christiana Figueres, climate justice activist Xiye Bastida, and writer, illustrator, and artist Oliver Jeffers.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Speedy Beet
There are few musical moments more well-worn than the first four notes of Beethoven's Fifth Symphony. But in this short, we find out that Beethoven might have made a last-ditch effort to keep his music from ever feeling familiar, to keep pushing his listeners to a kind of psychological limit. Big thanks to our Brooklyn Philharmonic musicians: Deborah Buck and Suzy Perelman on violin, Arash Amini on cello, and Ah Ling Neu on viola. And check out The First Four Notes, Matthew Guerrieri's book on Beethoven's Fifth. Support Radiolab today at Radiolab.org/donate.