Plant Molecular Biology

, Volume 63, Issue 1, pp 97–108

Nine 3-ketoacyl-CoA thiolases (KATs) and acetoacetyl-CoA thiolases (ACATs) encoded by five genes in Arabidopsis thaliana are targeted either to peroxisomes or cytosol but not to mitochondria

  • Chris Carrie
  • Monika W. Murcha
  • A. Harvey Millar
  • Steven M. Smith
  • James Whelan
Article

DOI: 10.1007/s11103-006-9075-1

Cite this article as:
Carrie, C., Murcha, M.W., Millar, A.H. et al. Plant Mol Biol (2007) 63: 97. doi:10.1007/s11103-006-9075-1

Abstract

The sub-cellular location of enzymes of fatty acid β-oxidation in plants is controversial. In the current debate the role and location of particular thiolases in fatty acid degradation, fatty acid synthesis and isoleucine degradation are important. The aim of this research was to determine the sub-cellular location and hence provide information about possible functions of all the putative 3-ketoacyl-CoA thiolases (KAT) and acetoacetyl-CoA thiolases (ACAT) in Arabidopsis. Arabidopsis has three genes predicted to encode KATs, one of which encodes two polypeptides that differ at the N-terminal end. Expression in Arabidopsis cells of cDNAs encoding each of these KATs fused to green fluorescent protein (GFP) at their C-termini showed that three are targeted to peroxisomes while the fourth is apparently cytosolic. The four KATs are also predicted to have mitochondrial targeting sequences, but purified mitochondria were unable to import any of the proteins in vitro. Arabidopsis also has two genes encoding a total of five different putative ACATs. One isoform is targeted to peroxisomes as a fusion with GFP, while the others display no targeting in vivo as GFP fusions, or import into isolated mitochondria. Analysis of gene co-expression clusters in Arabidopsis suggests a role for peroxisomal KAT2 in β-oxidation, while KAT5 co-expresses with genes of the flavonoid biosynthesis pathway and cytosolic ACAT2 clearly co-expresses with genes of the cytosolic mevalonate biosynthesis pathway. We conclude that KATs and ACATs are present in the cytosol and peroxisome, but are not found in mitochondria. The implications for fatty acid β-oxidation and for isoleucine degradation in mitochondria are discussed.

Keywords

Thiolase Mitochondria Peroxisomes β-oxidation Sub-cellular localization 

Abbreviations

AOX

Alternative oxidase

ACAT

Acetoacetyl-CoA thiolase

KAT

3-Ketoacyl-CoA thiolase

Rubisco SSU

Small subunit of Ribulose 1,5-bisphosphate carboxylase/oxygenase

Supplementary material

11103_2006_9075_MOESM1_ESM.doc (110 kb)
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11103_2006_9075_MOESM5_ESM.xls (43 kb)
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Copyright information

© Springer Science+Business Media B.V. 2006

Authors and Affiliations

  • Chris Carrie
    • 1
  • Monika W. Murcha
    • 1
  • A. Harvey Millar
    • 1
  • Steven M. Smith
    • 1
  • James Whelan
    • 1
  1. 1.ARC Centre of Excellence in Plant Energy BiologyUniversity of Western AustraliaCrawleyAustralia

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