A novel fatty Acyl-CoA Synthetase is required for pollen development and sporopollenin biosynthesis in Arabidopsis

Clarice de Azevedo Souza, Sung Soo Kim, Stefanie Koch, Lucie Kienow, Katja Schneider, Sarah M McKim, George W. Haughn, Erich Kombrink, Carl J Douglas

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Abstract

Acyl-CoA Synthetase (ACOS) genes are related to 4-coumarate:CoA ligase (4CL) but have distinct functions. The Arabidopsis thaliana ACOS5 protein is in clade A of Arabidopsis ACOS proteins, the clade most closely related to 4CL proteins. This clade contains putative nonperoxisomal ACOS enzymes conserved in several angiosperm lineages and in the moss Physcomitrella patens. Although its function is unknown, ACOS5 is preferentially expressed in the flowers of all angiosperms examined. Here, we show that an acos5 mutant produced no pollen in mature anthers and no seeds by self-fertilization and was severely compromised in pollen wall formation apparently lacking sporopollenin or exine. The phenotype was first evident at stage 8 of anther development and correlated with maximum ACOS5 mRNA accumulation in tapetal cells at stages 7 to 8. Green fluorescent protein-ACOS5 fusions showed that ACOS5 is located in the cytoplasm. Recombinant ACOS5 enzyme was active against oleic acid, allowing kinetic constants for ACOS5 substrates to be established. Substrate competition assays indicated broad in vitro preference of the enzyme for medium-chain fatty acids. We propose that ACOS5 encodes an enzyme that participates in a conserved and ancient biochemical pathway required for sporopollenin monomer biosynthesis that may also include the Arabidopsis CYP703A2 and MS2 enzymes.

Original languageEnglish
Pages (from-to)507-25
Number of pages19
JournalPlant Cell
Volume21
Issue number2
DOIs
Publication statusPublished - 20 Mar 2009

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Keywords

  • Alleles
  • Arabidopsis
  • Arabidopsis Proteins
  • Binding, Competitive
  • Biopolymers
  • Carotenoids
  • Coenzyme A Ligases
  • Cytoplasm
  • Flowers
  • Green Fluorescent Proteins
  • Kinetics
  • Mutation
  • Phylogeny
  • Pollen
  • Recombinant Fusion Proteins
  • Substrate Specificity
  • Journal Article
  • Research Support, Non-U.S. Gov't

Cite this

de Azevedo Souza, C., Kim, S. S., Koch, S., Kienow, L., Schneider, K., McKim, S. M., Haughn, G. W., Kombrink, E., & Douglas, C. J. (2009). A novel fatty Acyl-CoA Synthetase is required for pollen development and sporopollenin biosynthesis in Arabidopsis. Plant Cell, 21(2), 507-25. https://doi.org/10.1105/tpc.108.062513