Targeting of the polyhydroxybutyrate biosynthetic pathway to the plastids of Arabidopsis thaliana results in high levels of polymer accumulation
- Carnegie Institution of Washington, Stanford, CA (United States)
In the bacterium Alcaligenes eutrophus, three genes encode the enzymes necessary to catalyze the synthesis of poly[(R)-(-)-3-hydroxybutyrate] (PHB) from acetyl-CoA. In order to target these enzymes into the plastids of higher plants, the genes were modified by addition of DNA fragments encoding a pea chloroplast transit peptide, a constitutive plant promoter, and a poly(A) addition sequence. Each of the modified bacterial genes was introduced into Arabidopsis thaliana by Agrobacterium-mediated transformation, and plants containing all three genes were obtained by sexual crosses. These plans accumulated PHB up to 14% of the dry weight as 0.2- to 0.7-[mu]m granules within plastids. In contrast to earlier experiments in which expression of the PHB biosynthetic pathway in the cytoplasm led to a deleterious effect on growth, expression of the PHB biosynthetic pathway in plastids had no obvious effect on the growth or fertility of the transgenic plants and resulted in a 100-fold increase in the amount of PHB in higher plants. The high level of PHB accumulation also suggests that the synthesis of plastid acetyl-CoA is regulated by a mechanism which responds to metabolic demand. 20 refs., 6 figs.
- DOE Contract Number:
- FG02-94ER20133
- OSTI ID:
- 6707023
- Journal Information:
- Proceedings of the National Academy of Sciences of the United States of America; (United States), Vol. 91:26; ISSN 0027-8424
- Country of Publication:
- United States
- Language:
- English
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