title: High-yield production of a human therapeutic protein in tobacco chloroplasts.
abstract: Transgenic 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.
authors.affiliation: Monsanto Company, 700 Chesterfield Village Parkway North, St. Louis, MO 63198, USA. jeffrey.m.staub@monsanto.com
authors.forename: J M
authors.initials: JM
authors.lastname: Staub
authors.forename: B
authors.initials: B
authors.lastname: Garcia
authors.forename: J
authors.initials: J
authors.lastname: Graves
authors.forename: P T
authors.initials: PT
authors.lastname: Hajdukiewicz
authors.forename: P
authors.initials: P
authors.lastname: Hunter
authors.forename: N
authors.initials: N
authors.lastname: Nehra
authors.forename: V
authors.initials: V
authors.lastname: Paradkar
authors.forename: M
authors.initials: M
authors.lastname: Schlittler
authors.forename: J A
authors.initials: JA
authors.lastname: Carroll
authors.forename: L
authors.initials: L
authors.lastname: Spatola
authors.forename: D
authors.initials: D
authors.lastname: Ward
authors.forename: G
authors.initials: G
authors.lastname: Ye
authors.forename: D A
authors.initials: DA
authors.lastname: Russell
mesh_terms: D015153:Blotting, Western; D002455:Cell Division; D002460:Cell Line; D002736:Chloroplasts / Q000378:metabolism*; D004220:Disulfides; D004305:Dose-Response Relationship, Drug; D005818:Genetic Engineering / Q000379:methods; D018745:Genome, Plant; D019382:Human Growth Hormone / Q000096:biosynthesis*; D006801:Humans; D030821:Plants, Genetically Modified; D010947:Plants, Toxic; D018087:Plastids; D011994:Recombinant Proteins / Q000096:biosynthesis; D014026:Nicotiana / Q000378:metabolism*
chemical_list: D004220:Disulfides; D011994:Recombinant Proteins; D019382:Human Growth Hormone