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BIOCHEMICAL PROCESSES AND MACROMOLECULAR STRUCTURES

System Analysis of an Arabidopsis Mutant Altered in de Novo Fatty Acid Synthesis Reveals Diverse Changes in Seed Composition and Metabolism^1,[W],[OA]

Interdisciplinary Plant Group and Division of Biochemistry (M.C., B.P.M., M.H., J.J.T.), Computer Science Department (T.J., D.X.), DNA Core Microarray Facility (M.Z.), and Charles Gehrke Proteomics Center (B.P.M.), Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211

Embryo-specific overexpression of biotin carboxyl carrier protein 2 (BCCP2) inhibited plastid acetyl-coenzyme A carboxylase (ACCase), resulting in altered oil, protein, and carbohydrate composition in mature Arabidopsis (Arabidopsis thaliana) seed. To characterize gene and protein regulatory consequences of this mutation, global microarray, two-dimensional difference gel electrophoresis, iTRAQ, and quantitative immunoblotting were performed in parallel. These analyses revealed that (1) transgenic overexpression of BCCP2 did not affect the expression of three other ACCase subunits; (2) four subunits to plastid pyruvate dehydrogenase complex were 25% to 70% down-regulated at protein but not transcript levels; (3) key glycolysis and de novo fatty acid/lipid synthesis enzymes were induced; (4) multiple storage proteins, but not cognate transcripts, were up-regulated; and (5) the biotin synthesis pathway was up-regulated at both transcript and protein levels. Biotin production appears closely matched to endogenous BCCP levels, since overexpression of BCCP2 produced mostly apo-BCCP2 and the resulting ACCase-compromised, low-oil phenotype. Differential expression of glycolysis, plastid pyruvate dehydrogenase complex, fatty acid, and lipid synthesis activities indicate multiple, complex regulatory responses including feedback as well as futile "feed-forward" elicitation in the case of fatty acid and lipid biosynthetic enzymes. Induction of storage proteins reveals that oil and protein synthesis share carbon intermediate(s) and that reducing malonyl-coenzyme A flow into fatty acids diverts carbon into amino acid and protein synthesis.

² Present address: Institute of Plant Genetics and Biotechnology, Slovak Academy of Sciences, Akademicka 2, P.O. Box 39A, SK–650 07 Nitra, Slovak Republic.

The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Jay J. Thelen (thelenj{at}missouri.edu).

^[W] The online version of this article contains Web-only data.

^[OA] Open Access articles can be viewed online without a subscription.

www.plantphysiol.org/cgi/doi/10.1104/pp.108.134882

^* Corresponding author; e-mail thelenj{at}missouri.edu.

Received December 30, 2008; accepted February 27, 2009; published March 11, 2009.

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