Rubber Biosynthesis

The goal of this project is to determine how natural rubber is synthesized in plants. Natural rubber is required for the manufacture of thousands of products needed in daily life. Due to its superior performance properties, natural rubber is an irreplaceable material in the manufacture of many products, such as automobile and aircraft tires. Surprisingly, even with its high economic and strategic importance, the biosynthesis of rubber has been poorly characterized. Move than fifty years of biochemical experimentation has so far failed to identify the proteins required for rubber biosynthesis in plants. This is primarily due to the fact that the membrane associated rubber biosynthetic machinery is resistant to purification by classic biochemical methods. To circumvent this problem, proteomics, genomics and reverse genetic analyses will be used to functionally identify the genes/proteins required for rubber biosynthesis from two hyper-producing rubber species, guayule (Parthenium argentatum) and Russian dandelion (Taraxacum kok-saghyz). The novel approach used here represents the most rapid means of advancing our knowledge of rubber biosynthesis in plants and will lead to identification of genes/proteins that regulate the quantity and quality of natural rubber.

The gene-based resources generated from this research will be used for the improvement of current rubber producing crops and the development of alternative rubber producing domestic crops through genetic engineering and molecular breeding approaches. The development of domestic rubber producing crops will provide a number of benefits to the American public including: 1) decreased dependence on imported natural rubber, 2) the creation of a new high value commodity crops for the American farmer, 3) the generation of a hypoallergenic alternatives to Hevea derived rubber for persons with latex allergies and 4) decreased dependence on petroleum for the synthesis of synthetic polymers.

Vitamin B1 (Thiamin) Biosynthesis In Plants

Thiamin (Vitamin B1) deficiencies in humans can lead to a condition known as Beriberi that is manifested by severe neurological disorders and a general wasting phenomenon. This disease is primarily associated with poverty-stricken populations of developing countries whose diets subsist primarily of polished grain products such as polished rice or bleached wheat flour. A sustainable solution to thiamin deficiencies in humans would be to increase the nutritional content of staple food crops that endogenous populations of the world commonly consume. By genetic engineering crops for increased thiamin, it should be possible to positively impact the nutritional needs of the global population. Unfortunately, the major impediment to this effort is a current lack of knowledge pertaining to the biosynthesis of thiamin in plants. We are using a combination of biochemical, molecular, and genomic-based approaches to dissect the regulatory mechanisms controlling thiamin biosynthesis in plants. The increased biosynthetic knowledge obtained through our research will be important for the rational design of crops engineered for elevated thiamin levels for improved human and animal nutrition.

BCH 400/600 Introductory Biochemistry

Ajjawi I, Shintani D. Engineered plants with elevated Vitamin E: a nutriceutical success story. Trends in Biotechnology 22, 104-107.

Branen, J.K., Shintani, D. and Engeseth, N.J. Expression of Antisense Acyl Carrier Protein-4 (LMI-ACP) Reduces Lipid Content in Arabidopsis Leaf Tissue. (2003) Plant Physiology 132:748-756.

Tsegaye, Y., Shintani, D.K., DellaPenna, D. (2002) Overexpression of the enzyme p-hydroxyphenylpyruvate dioxygenase in Arabidopsis and its relation to tocopherol biosynthesis. Plant Physiology and Biochemistry. (2002) 40: 913-920.

Tang, S.; Yu, J.-K.; Slabaugh, M. B.; Shintani, D. K.; Knapp, S. J. (2002) Simple sequence repeat map of the sunflower genome.    Theoretical and Applied Genetics 105(8): 1124-1136. 

Shintani DK, DellaPenna D. (2002) The role of 2-methyl-6-phytylbenzoquinone methytransferase in determining tocopherol composition in Synechocystis sp. PCC6803. FEBS 511: 1-5

Shintani DK, DellaPenna D (1998) Elevating the vitamin E content of plants through metabolic engineering. Science 282: 2098-2100.

Shintani DK, Roesler K, Shorrosh BS, Savage L, Ohlrogge JB (1997) Antisense expression and overexpression of biotin carboxylase in tobacco leaves. Plant Physiology 114: 881-886

Wada H, Shintani DK, Ohlrogge JB (1997) Why do mitochondria synthesize fatty acids? Evidence for involvement in lipoic acid production. Proc Natl Acad Sci USA 94: 1591‑1596.

Roesler K, Shintani D, Savage L, Boddupalli S, Ohlrogge J (1997) Targeting of the Arabidopsis homomeric acetyl-Coenzyme A carboxylase to plastids of rapeseeds. Plant Physiology 113: 75 – 81

Roesler K, Savage L, Shintani DK, Shorrosh BS, Ohlrogge JB (1996) Co-purification, co-immunoprecipitation, and coordinate expression during oilseed development of acetyl-CoA carboxylase activity, biotin carboxylase protein, and biotin carboxyl carrier protein from higher plants. Planta 198:517-525.

Shintani DK and Ohlrogge JB (1995) Feedback regulation of fatty acid synthesis in tobacco cell cultures. The Plant Journal 7: 577-587

Shorrosh BS, Roesler K, Shintani DK, Van De Loo F, Savage L, Ohlrogge JB (1995) Characterization of the biotin carboxylase subunit of the plastid localized acetyl-CoA carboxylase found in dicots. Plant Physiology 108: 805-812.

Shintani DK and Ohlrogge JB (1994) Characterization of a mitochondrial acyl carrier protein isoform isolated from Arabidopsis thaliana.  Plant Physiology 104: 1221-1229.

Houck CM, Shintani DK, Knauf VC (1993) The use of Agrobacterium as a gene transfer agent for plants.  In KG Mukerji, VP Singh eds, Frontiers in Applied Microbiology, vol. 4, Rastogi Publishing Company, pp 1-25.

Thompson GA, Scherer DE, Foxall-Van Aken S, Kenny JW, Young HL, Shintani DK, Kridl JC, Knauf VC (1991) Primary structure of the precursor and mature forms of stearoyl-acyl carrier protein desaturase from safflower embryos and requirement of ferredoxin for enzyme activity. Proc Natl Acad Sci USA 88: 2578-2582.