Nature Biotechnology
18, 333 - 338 (2000)
doi:10.1038/73796
High-yield production of a human therapeutic protein in tobacco chloroplasts
Jeffrey M. Staub1, Bradley Garcia2, Julie Graves2, Peter T. J. Hajdukiewicz1, Priscilla Hunter1, Narender Nehra1, Vikram Paradkar2, Michael Schlittler1, James A. Carroll1, Lori Spatola2, Dannette Ward1, Guangning Ye1
& Douglas A. Russell21
Monsanto Company, 700 Chesterfield Village
Parkway North, St. Louis, MO 63198. 2
Integrated Protein Technologies, Agracetus Campus,
Monsanto Company, 8520 University Green, Middleton,
WI 53562.
Correspondence should be addressed to Jeffrey M. Staub jeffrey.m.staub@monsanto.compharmaceuticalplastid transformationsomatotropintransplastomicubiquitin fusionTransgenic plants have become attractive systems for production of human
therapeutic proteins because of the reduced risk of mammalian viral contaminants,
the ability to do large scale-up at low cost, and the low maintenance requirements.
Here we report a feasibility study for production of a human therapeutic protein
through transplastomic transformation technology, which has the additional
advantage of increased biological containment by apparent elimination of the
transmission of transgenes through pollen. We show that chloroplasts can express
a secretory protein, human somatotropin, in a soluble, biologically active,
disulfide-bonded form. High concentrations of recombinant protein accumulation
are observed (>7% total soluble protein), more than 300-fold higher than a
similar gene expressed using a nuclear transgenic approach. The plastid-expressed
somatotropin is nearly devoid of complex post-translational modifications,
effectively increasing the amount of usable recombinant protein. We also describe
approaches to obtain a somatotropin with a non-methionine N terminus, similar
to the native human protein. The results indicate that chloroplasts are a
highly efficient vehicle for the potential production of pharmaceutical proteins
in plants.
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