ISSN:
1573-5028
Keywords:
endosperm-specific expression
;
lysine-rich γ-zein
;
maize endosperm transient transformation
;
γ-zein gene
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract During maize seed development, endosperm cells synthesize large amounts of storage proteins, α-, β, and γ-zeins, which accumulate within endoplasmic reticulum (ER)-derived protein bodies. The absence of lysine in all zein polypeptides results in an imbalance in the amino acid composition of maize seeds. We modified the maize γ-zein gene through the introduction of lysine-rich (Pro-Lys)n coding sequences at different sites of the γ-zein coding sequence. Maize endosperms were transiently transformed by biolistic bombardment with Lys-rich γ-zein constructs under the control of the 1.7 kb γ-zein seed-specific promoter and the cauliflower mosaic virus (CaMV) 35S promoter. When (Pro-Lys)n sequences were inserted contiguous to or in substitution of the Pro-Xaa region of the γ-zein, high levels of protein were observed. In contrast, when (Pro-Lys)n sequences were inserted five residues from the C-terminal, the transcript was present but modified protein was not detected. These results suggest that only an appropriate positioning of Lys-rich inserts leads to the modified molecule displaying correct folding and stability. Subcellular localization analyses and immunoelectron microscopy studies on isolated protein bodies demonstrated that modified γ-zeins accumulate within these organelles and co-localized with endogenous - and γ-zeins. The studies reported here show the feasibility of manipulating the γ-zein gene in order to obtain stable and correctly targeted Lys-rich zeins in maize seeds.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1005889314967
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