ABSTRACT
An emerging strategy in biomanufacturing involves using transgenic plants to express recombinant pharmaceutical and industrial proteins in large quantities. ß-Site APP cleaving enzyme 1 (ß-secretase 1, BACE1) is an enzyme involved in the abnormal production of Aß42, the major component of senile plaques in Alzheimer's disease (AD). Thus, BACE1 represents a key target protein in the development of new potential drugs to treat Alzheimer's disease. We aimed to develop a tomato-derived recombinant BACE1 (rBACE1) protein to serve as a vaccine antigen that would promote an immune response. We utilized a plant expression cassette, pE8BACE, to optimize BACE1 expression in tomato fruits. Polyemerase chain reaction and Southern blot analyses verified integration of the BACE1 gene into the plant genome. Northern and Western blot analyses demonstrated successful mRNA and protein expression of rBACE1, respectively; the Sensizyme assay kit estimated the expression level of rBACE1 protein at 136 ± 7 ng mg⻹ total soluble protein. The tomato-derived rBACE1 retains its activity for a long storage period at cool or room temperature, and is highly resistant to degradation in conditions such as low acidity. Tomato-derived rBACE1 was severely degraded by heat or boiling. The proteolytic activity of tomato-derived rBACE1, confirmed by fluorescence resonance transfer assay, was similar to that of a commercial sample of Escherichia coli-derived BACE1.
Subject(s)
Alzheimer Vaccines/genetics , Amyloid Precursor Protein Secretases/genetics , Amyloid Precursor Protein Secretases/metabolism , Aspartic Acid Endopeptidases/genetics , Aspartic Acid Endopeptidases/metabolism , Fruit/genetics , Plants, Genetically Modified/genetics , Solanum lycopersicum/genetics , Alzheimer Disease/enzymology , Alzheimer Disease/immunology , Alzheimer Disease/prevention & control , Amyloid Precursor Protein Secretases/isolation & purification , Aspartic Acid Endopeptidases/isolation & purification , Gene Expression , Genetic Vectors , Humans , Recombinant Proteins/genetics , Recombinant Proteins/isolation & purification , Recombinant Proteins/metabolismABSTRACT
In an attempt to develop an edible vaccine, we transformed a recombinant hepatitis B virus (HBV) gene encoding the middle protein of HBV that contains the surface S and preS2 antigen into potato by Agrobacterium-mediated transformation. The HBV gene was under control of either the CaMV 35S promoter, the double 35S promoter with the AlMV 5' non-translated leader sequence, or the tuber-specific patatin promoter. HBV mRNA levels were higher with the 35S promoter than with the double 35S and patatin promoters; however, the levels of the S and preS2 antigen in the transformed tubers were higher with the patatin promoter than with the CaMV 35S and double promoters. The levels of preS2 antigen produced are the highest reported to date. Transgenic potato tubers were fed to mice, and the mice showed an immune response against the HBV S antigen.
