title: Purification, characterization and safety assessment of the introduced cold shock protein B in DroughtGard maize.
abstract: DroughtGard maize was developed through constitutive expression of cold shock protein B (CSPB) from Bacillus subtilis to improve performance of maize (Zea mays) under water-limited conditions. B. subtilis commonly occurs in fermented foods and CSPB has a history of safe use. Safety studies were performed to further evaluate safety of CSPB introduced into maize. CSPB was compared to proteins found in current allergen and protein toxin databases and there are no sequence similarities between CSPB and known allergens or toxins. In order to validate the use of Escherichia coli-derived CSPB in other safety studies, physicochemical and functional characterization confirmed that the CSPB produced by DroughtGard possesses comparable molecular weight, immunoreactivity, and functional activity to CSPB produced from E. coli and that neither is glycosylated. CSPB was completely digested with sequential exposure to pepsin and pancreatin for 2 min and 30 s, respectively, suggesting that CSPB will be degraded in the mammalian digestive tract and would not be expected to be allergenic. Mice orally dosed with CSPB at 2160 mg/kg, followed by analysis of body weight gains, food consumption and clinical observations, showed no discernible adverse effects. This comprehensive safety assessment indicated that the CSPB protein from DroughtGard is safe for food and feed consumption.
authors.affiliation: Monsanto Company, 800 North Lindbergh Blvd, St. Louis, MO 63167, United States. Electronic address: cunxi.wang@monsanto.com.
authors.forename: Cunxi
authors.initials: C
authors.lastname: Wang
authors.affiliation: Monsanto Company, 800 North Lindbergh Blvd, St. Louis, MO 63167, United States.
authors.forename: Luis A
authors.initials: LA
authors.lastname: Burzio
authors.affiliation: Monsanto Company, 800 North Lindbergh Blvd, St. Louis, MO 63167, United States.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Koch
authors.affiliation: Monsanto Company, 800 North Lindbergh Blvd, St. Louis, MO 63167, United States.
authors.forename: Andre
authors.initials: A
authors.lastname: Silvanovich
authors.affiliation: Monsanto Company, 800 North Lindbergh Blvd, St. Louis, MO 63167, United States. Electronic address: Erin.bell@monsanto.com.
authors.forename: Erin
authors.initials: E
authors.lastname: Bell
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects / Q000502:physiology; D002352:Carrier Proteins / Q000008:administration & dosage* / Q000009:adverse effects / Q000302:isolation & purification*; D004435:Eating / Q000187:drug effects / Q000502:physiology; D029968:Escherichia coli Proteins / Q000008:administration & dosage* / Q000009:adverse effects / Q000302:isolation & purification*; D005260:Female; D006360:Heat-Shock Proteins / Q000008:administration & dosage* / Q000009:adverse effects / Q000302:isolation & purification*; D008297:Male; D051379:Mice; D016601:RNA-Binding Proteins; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods; D003313:Zea mays / Q000009:adverse effects
chemical_list: D002352:Carrier Proteins; C491179:CspB protein, E coli; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D016601:RNA-Binding Proteins
keywords: Cold shock protein B; Digestibility; DroughtGard™; Equivalence; History of safe use; Protein purification; Safety assessment; Toxicity