LAP6/POLYKETIDE SYNTHASE AandLAP5/POLYKETIDE SYNTHASE BEncode Hydroxyalkyl α-Pyrone Synthases Required for Pollen Development and Sporopollenin Biosynthesis inArabidopsis thaliana
| Autor: | Erich Kombrink, Dae-Yeon Suh, Daniel Krahn, Sung-Soo Kim, Dimitri Heintz, Che C. Colpitts, Benjamin Lallemand, Michel Legrand, Etienne Grienenberger, Thierry Heitz, Markus Kaiser, Sun Young Kim, Carl J. Douglas, Clarice de Azevedo Souza, Pierrette Geoffroy |
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| Rok vydání: | 2010 |
| Předmět: |
Arabidopsis
Plant Science Genes Plant Pollen exine formation Polyketide chemistry.chemical_compound Biopolymers Microscopy Electron Transmission Sporopollenin Biosynthesis Polyketide synthase Arabidopsis thaliana Alleles In Situ Hybridization Research Articles biology Arabidopsis Proteins Reverse Transcriptase Polymerase Chain Reaction food and beverages Cell Biology biology.organism_classification Carotenoids Recombinant Proteins Kinetics Biochemistry chemistry Mutation biology.protein Pollen Biologie Polyketide Synthases Pollen wall |
| Zdroj: | The Plant Cell. 22:4045-4066 |
| ISSN: | 1532-298X 1040-4651 |
| Popis: | Plant type III polyketide synthases (PKSs) catalyze the condensation of malonyl-CoA units with various CoA ester starter molecules to generate a diverse array of natural products. The fatty acyl-CoA esters synthesized by Arabidopsis thaliana ACYL-COA SYNTHETASE5 (ACOS5) are key intermediates in the biosynthesis of sporopollenin, the major constituent of exine in the outer pollen wall. By coexpression analysis, we identified two Arabidopsis PKS genes, POLYKETIDE SYNTHASE A (PKSA) and PKSB (also known as LAP6 and LAP5, respectively) that are tightly coexpressed with ACOS5. Recombinant PKSA and PKSB proteins generated tri-and tetraketide α-pyrone compounds in vitro from a broad range of potential ACOS5-generated fatty acyl-CoA starter substrates by condensation with malonyl-CoA. Furthermore, substrate preference profile and kinetic analyses strongly suggested that in planta substrates for both enzymes are midchain- and ω-hydroxylated fatty acyl-CoAs (e.g., 12-hydroxyoctadecanoyl-CoA and 16-hydroxyhexadecanoyl-CoA), which are the products of sequential actions of anther-specific fatty acid hydroxylases and acyl-CoA synthetase. PKSA and PKSB are specifically and transiently expressed in tapetal cells during microspore development in Arabidopsis anthers. Mutants compromised in expression of the PKS genes displayed pollen exine layer defects, and a double pksa pksb mutant was completely male sterile, with no apparent exine. These results show that hydroxylated α-pyrone polyketide compounds generated by the sequential action of ACOS5 and PKSA/B are potential and previously unknown sporopollenin precursors. |
| Databáze: | OpenAIRE |
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