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German biotechnology company ICON Genetics is to start field trials of a
transgenic tobacco crop that will be used to produce an enzyme with
potential as an active pharmaceutical ingredient and as a catalyst for the
manufacture of industrial chemicals, July 2005.

The field trial, carried out in collaboration with the Kentucky Tobacco
Research and Development Centre (KTRDC) in Lexington, US, will involve
transgenic plants with genetically engineered chloroplasts containing a
phenylalanine ammonia lyase (PAL) gene from Arabidopsis thaliana.

An overexpression of the PAL gene in tobacco chloroplasts aims at both
pharmaceutical and industrial applications: the purified enzyme can serve as
a drug for the treatment of the inherited disease phenylketonuria (PKU). The
enzyme also serves as a biocatalyst for industrial biochemical synthesis,
particularly chiral compounds. Futhermore, expression of PAL in the plants
will lead to the accumulation of metabolites from the phenylpropane pathway
that are also of commercial value, according to Icon.

Making pharmaceuticals in crop plants such as tobacco is an attractive
proposition because they are inexpensive to grow, and could produce vast
quantities of drugs or vaccines at low cost, potentially making it possible
to make drugs that were not economically feasible before. But moves in this
area have been met with dismay by environmentalist groups, alarmed that the
GM traits could find their way into the food chain.

ICON said that biosafety aspects of the field trial, which has been granted
a release permit by the US Government?s Animal and Plant Health Inspection
Service, have been ?carefully considered?.

The firm maintains that chloroplast-located transgenes generally do not
spread into the environment via pollen flow. Moreover, the genetically
engineered plants do not contain antibiotic resistance genes, according to
the company, since they were created using ICON's proprietary resistance
marker removal technology.

"The tobacco plants do not contain any foreign genetic sequences except
those required for PAL protein biosynthesis. Expression is achieved by
extending an existing operon, thus additional promoter elements, which may
lead to genetic instability, are not required," explained ICON?s manager,
Christian Eibl.

[www.in-pharmatechnologist.com]

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