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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
2001-9-4
pubmed:abstractText
The B subunits of enterotoxigenic Escherichia coli (LTB) and cholera toxin of Vibrio cholerae (CTB) are candidate vaccine antigens. Integration of an unmodified CTB-coding sequence into chloroplast genomes (up to 10,000 copies per cell), resulted in the accumulation of up to 4.1 % of total soluble tobacco leaf protein as functional oligomers (410-fold higher expression levels than that of the unmodified LTB gene expressed via the nuclear genome). However, expression levels reported are an underestimation of actual accumulation of CTB in transgenic chloroplasts, due to aggregation of the oligomeric forms in unboiled samples similar to the aggregation observed for purified bacterial antigen. PCR and Southern blot analyses confirmed stable integration of the CTB gene into the chloroplast genome. Western blot analysis showed that the chloroplast- synthesized CTB assembled into oligomers and were antigenically identical with purified native CTB. Also, binding assays confirmed that chloroplast-synthesized CTB binds to the intestinal membrane GM1-ganglioside receptor, indicating correct folding and disulfide bond formation of CTB pentamers within transgenic chloroplasts. In contrast to stunted nuclear transgenic plants, chloroplast transgenic plants were morphologically indistinguishable from untransformed plants, when CTB was constitutively expressed in chloroplasts. Introduced genes were inherited stably in subsequent generations, as confirmed by PCR and Southern blot analyses. Increased production of an efficient transmucosal carrier molecule and delivery system, like CTB, in transgenic chloroplasts makes plant-based oral vaccines and fusion proteins with CTB needing oral administration commercially feasible. Successful expression of foreign genes in transgenic chromoplasts and availability of marker-free chloroplast transformation techniques augurs well for development of vaccines in edible parts of transgenic plants. Furthermore, since the quaternary structure of many proteins is essential for their function, this investigation demonstrates the potential for other foreign multimeric proteins to be properly expressed and assembled in transgenic chloroplasts.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0022-2836
pubmed:author
pubmed:copyrightInfo
Copyright 2001 Academic Press.
pubmed:issnType
Print
pubmed:day
31
pubmed:volume
311
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1001-9
pubmed:dateRevised
2006-4-21
pubmed:meshHeading
pubmed-meshheading:11531335-Blotting, Southern, pubmed-meshheading:11531335-Blotting, Western, pubmed-meshheading:11531335-Chloroplasts, pubmed-meshheading:11531335-Cholera Toxin, pubmed-meshheading:11531335-Enzyme-Linked Immunosorbent Assay, pubmed-meshheading:11531335-Escherichia coli, pubmed-meshheading:11531335-G(M1) Ganglioside, pubmed-meshheading:11531335-Gene Expression, pubmed-meshheading:11531335-Genetic Vectors, pubmed-meshheading:11531335-Genome, Plant, pubmed-meshheading:11531335-Plants, Genetically Modified, pubmed-meshheading:11531335-Plants, Toxic, pubmed-meshheading:11531335-Polymerase Chain Reaction, pubmed-meshheading:11531335-Protein Binding, pubmed-meshheading:11531335-Protein Structure, Quaternary, pubmed-meshheading:11531335-Protein Subunits, pubmed-meshheading:11531335-Recombination, Genetic, pubmed-meshheading:11531335-Tobacco, pubmed-meshheading:11531335-Transgenes, pubmed-meshheading:11531335-Vaccines, Edible, pubmed-meshheading:11531335-Vibrio cholerae
pubmed:year
2001
pubmed:articleTitle
Expression of the native cholera toxin B subunit gene and assembly as functional oligomers in transgenic tobacco chloroplasts.
pubmed:affiliation
Department of Molecular Biology and Microbiology and Center for Discovery of Drugs and Diagnostics, University of Central Florida, 12722 Research Parkway, Orlando, FL 32826-3227, USA. daniell@mail.ucf.edu
pubmed:publicationType
Journal Article