Catalytic antibodies active in plants
By Daniela Kenzelmann, Checkbiotech

Israeli scientists have found a novel strategy to confer herbicide-resistance to plants. The new approach uses catalytic antibodies which can destroy certain types of herbicides.

Traditionally, herbicide-resistant crops were generated by breeding under selective pressure or crossing with herbicide-resistant species. More recently, genetically modified plants can be generated for this purpose.

Prof. Ehud Keinan of the Technion – Israel Institute of Technology and his collaborators at the Hebrew University in Rehovot demonstrate in “Herbide-resistance conferred by expression of a catalytic antibody in Arabidopsis thaliana” that so-called catalytic antibodies can be used to confer a new trait to plants.

What are catatlytic antibodies? Catalysts are defined as agents, which accelerate a chemical reaction without being consumed by it. Antibodies have the characteristic feature of specifically recognizing and binding to their target. These two characteristics combined result in catalytic antibodies.

The goal of Prof. Keinan’s team was to generate a plant that could produce a new enzyme that would decompose herbicides called carbamate compounds. This group of herbicides is commonly used to prevent weeds from germinating.

Since two genes are necessary to make an antibody, an important step in their work was to confirm that both of these subunits (the so-called heavy chain and light chain) can assemble in a plant to form a functioning catalytic antibody.

With that in mind, the researchers generated two separate transgenic plant lines, one containing the heavy chain, and the other containing the light chain of the antibody. Then, the two lines were crossed, resulting in a variety that was able to produce the desired catalytic antibody.

Prof. Keinan’s laboratory still needed to confirm, however, that the genetically engineered varieties produced a functioning catalytic antibody. That is why the research team ran a test for aldolase activity in the new antibody-containing varieties, which is present when carbamate herbicides are degraded. Not only did they detect aldolase activity, but they were also able to show that the novel plant line was resistant to carbamate herbicide.

Prof. Keinan, working at the Technion in Haifa as well as at The Scripps Research Institute in La Jolla, California, explains, “Certainly, our immediate goal was benefiting plant breeding, but our work has much broader implications, suggesting that in vivo expression of catalytic antibodies could become a general strategy for phenotype modification not only in plants, but also in other organisms.”

“The key message is that an appropriately designed catalytic antibody could solve any problem that can be defined in the form of a chemical reaction, for example the destruction of various toxins.” So far, catalytic antibodies have been shown to mediate more than 100 different reactions in laboratories studies, thus opening up a broad range of new possibilities in chemical, biotechnological, agricultural, and medical fields.

Before catalytic antibodies conferring herbicide resistance to plants can be used in agriculture, the method needs to be further developed. However, due to the work from Prof. Keinan’s team, significant groundwork has been laid that proves that catalytic antibodies can modify a plant’s properties.

Daniela Kenzelmann is a Science Journalist for Checkbiotech and is writing her PhD at the Friedrich Miescher Institute in Basel, Switzerland. Contact her at daniela.kenzelmann@fmi.ch

Herbicide-resistance conferred by expression of a catalytic antibody in Arabidopsis thaliana
Weiss Y et al.
Nature Biotechnology, 2006 Jun, 24(6):713-7

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=Abstract&list_uids=16751769&query_hl=1&itool=pubmed_docsum

Prof. Ehud Keinan
Department of Chemistry
Technion-Israel Institute of Technology
Technion City, Haifa 32000, Israel.

USA address:
The Scripps Research Institute
Department of Molecular Biology
10550 North Torrey Pines Road, MB-20, La Jolla, CA 92037

http://www.technion.ac.il/

http://www.scripps.edu/research/faculty.php?rec_id=1358

http://www.minerva.mpg.de/minerva_centers/center_03.html