title: Protein accumulation and rumen stability of wheat γ-gliadin fusion proteins in tobacco and alfalfa.
abstract: The nutritional value of various crops can be improved by engineering plants to produce high levels of proteins. For example, because methionine deficiency limits the protein quality of Medicago Sativa (alfalfa) forage, producing alfalfa plants that accumulate high levels of a methionine-rich protein could increase the nutritional value of that crop. We used three strategies in designing methionine-rich recombinant proteins that could accumulate to high levels in plants and thereby serve as candidates for improving the protein quality of alfalfa forage. In tobacco, two fusion proteins, γ-gliadin-δ-zein and γ-δ-zein, as well as δ-zein co-expressed with β-zein, all formed protein bodies. However, the γ-gliadin-δ-zein fusion protein accumulated to the highest level, representing up to 1.5% of total soluble protein (TSP) in one transformant. In alfalfa, γ-gliadin-δ-zein accumulated to 0.2% of TSP, and in an in vitro rumen digestion assay, γ-gliadin-δ-zein was more resistant to microbial degradation than Rubisco. Additionally, although it did not form protein bodies, a γ-gliadin-GFP fusion protein accumulated to much higher levels, 7% of TSP, than a recombinant protein comprised of an ER localization signal fused to GFP in tobacco. Based on our results, we conclude that γ-gliadin-δ-zein is a potential candidate protein to use for enhancing methionine levels in plants and for improving rumen stability of forage protein. γ-gliadin fusion proteins may provide a general platform for increasing the accumulation of recombinant proteins in transgenic plants.
authors: Public Intellectual Property Resource for Agriculture, Department of Plant Sciences, University of California, Davis, CA, USA.
authors: Xiaodong
authors: X
authors: Sun
authors: Public Intellectual Property Resource for Agriculture, Department of Plant Sciences, University of California, Davis, CA, USA.
authors: Cecilia L
authors: CL
authors: Chi-Ham
authors: Department of Plant Sciences, University of California, Davis, CA, USA.
authors: Tamar
authors: T
authors: Cohen-Davidyan
authors: Department of Plant Sciences, University of California, Davis, CA, USA.
authors: Christopher
authors: C
authors: DeBen
authors: Department of Animal Science, University of California, Davis, CA, USA.
authors: Girma
authors: G
authors: Getachew
authors: Department of Animal Science, University of California, Davis, CA, USA.
authors: Edward
authors: E
authors: DePeters
authors: Department of Plant Sciences, University of California, Davis, CA, USA.
authors: Daniel
authors: D
authors: Putnam
authors: Public Intellectual Property Resource for Agriculture, Department of Plant Sciences, University of California, Davis, CA, USA.
authors: Alan
authors: A
authors: Bennett
mesh_terms: D000818:Animals; D005903:Gliadin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000455:Medicago sativa / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D012417:Rumen / Q000378:metabolism*; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism*; D014908:Triticum / Q000737:chemistry
chemical_list: D005903:Gliadin
keywords: KDEL; N-terminal γ-gliadin; alfalfa; protein accumulation; rumen stability; tobacco