A new paradigm for regulation of de novo fatty acid synthesis in plants

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This project will enhance our understanding of fatty acid synthesis in plants as an important step in developing new strategies for engineering designer oilseeds of the future. Plant oils are a valuable renewable resource for food, fuels and chemicals. The genes that encode the enzymes responsible for lipid synthesis have been identified, but regulation of these genes is still poorly understood. This project will take a multi-disciplinary approach to study the role of newly discovered proteins in regulating a key early step in fatty acid synthesis, which in turn controls total plant oil accumulation. The project will prepare two undergraduate students, including underrepresented minorities, and two graduate students for STEM careers. They will be trained in modern research approaches of plant biotechnology, genetics, and protein science. The undergraduates from University of Southern Mississippi (USM; an especially diverse student population) will travel to University of Missouri (MU) to join the MU undergraduates for a 9-week intensive summer research experience for undergraduates in the Thelen and Van Doren laboratories. The graduate students at MU and USM will acquire transferable skills from formal training in mentoring and science communication and by mentoring the undergraduate students in research.This project leverages the expertise of a multi-disciplinary team to test the hypothesis that the newly discovered biotin attachment domain-containing (BADC) gene family and its counterpart biotin carboxyl carrier protein (BCCP) collectively act as a molecular rheostat to modulate acetyl CoA carboxylase (ACCase) activity and ultimately seed oil accumulation. Quantitative biophysical analyses will distinguish between two hypotheses for how BADC proteins intercalate into the holo-ACCase complex and reduce enzymatic activity. The analyses will test the alternatives of the BADC structure in solution versus its affinity for the BC subunit enabling BADC to compete with its functional, catalytic sibling protein, BCCP, for access to ACCase. The regulatory role of BADCs during seed development and induced regulation of fatty acid synthesis (FAS) will be characterized by quantifying gene expression and absolute protein levels of the BADC regulatory proteins relative to the ACCase enzyme, under various states of FAS. The rheostat hypothesis will be tested in planta by modulating BADC protein levels and quantifying carbon flux through ACCase and FAS and the effect on total oil accumulation. Additionally, the ability of BADC proteins to alleviate the FAS feedback inhibition that is induced in plants engineered to produce novel oils will be tested. This will clarify metabolic bottlenecks that limit oilseed engineering.