Jin, Huanan , Nikolau, Basil J .
Genetic, Biochemical and Physiological Studies Acetyl-CoA Metabolism via Condensation.
Acetyl-CoA is metabolized via one of three mechanisms, carboxylation, acetylation and condensation. Acetoacetyl-CoA thiolase (AACT) catalyzes the condensation of two acetyl-CoA molecules to form acetoacetyl-CoA. The fate of acetoacetyl-CoA depends on the biological context in which it is generated. In the cytosol of plant cells, it is the precursor of mevalonate-derived isoprenoids. In microbes, such as Rhodospirillum rubrum, acetoacetyl-CoA is the precursor of the storage polymer polyhydroxybutyrate (PHB). BLASTP analyses have identified two AACT genes in the Arabidopsis genome, At5g47720 (AACT1) and At5g48230 (AACT2). These two genes code for proteins that share 75% sequence identity. Two T-DNA insertion alleles at each AACT gene have been characterized. These characterizations indicate that although both genes are expressed (as evidenced by RT-PCR analysis), mutations in AACT2 are embryo lethal, whereas null alleles of AACT1 are viable and show no apparent growth phenotypes. Additional physiological, morphological, ultrastructural and expression characterizations of these mutants will be conducted. In R. rubrum, the AACT enzyme is encoded within the phaABC operon, which is responsible for PHB biosynthesis. Furthermore, R. rubrum contains two additional AACT-like genes, called phaC2 and phaC3. To characterize the roles of these genes in acetyl-CoA metabolism, we have generated antibodies to each gene product. In addition, we have developed an inducible-expression system for individually over-expressing each pha gene. In combination, these studies will elucidate the role of AACT in the acetyl-CoA metabolic network.
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1 - Iowa State University, Department of Biochemistry, Biophysics and Molecular Biology, Molecular Biology Building 2254, Ames, IA, 50011, U.S.A.
2 - Iowa State University, Department of Biochemistry, Biophysics and Molecular Biology
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM