Abstract
The first step of peroxisomal fatty acid beta -oxidation is catalyzed by a family of acyl-CoA oxidase isozymes with distinct fatty acyl-CoA chain-length specificities. Here we identify a new acyl-CoA oxidase gene from Arabidopsis (AtACX3) following the isolation of a promoter-trapped mutant in which beta -glucuronidase expression was initially detected in the root meristem. In acx3 mutant seedlings medium-chain acyl-CoA oxidase activity was reduced by 95%, whereas long- and short-chain activities were unchanged. Despite this reduction in activity lipid catabolism and seedling development were not perturbed. AtACX3 was cloned and expressed in Escherichia coli. The recombinant enzyme displayed medium-chain acyl-CoA substrate specificity. Analysis of beta -glucuronidase activity in acx3 revealed that, in addition to constitutive expression in the root axis, AtACX3 is also up-regulated strongly in the hypocotyl and cotyledons of germinating seedlings. This suggests that beta -oxidation is regulated predominantly at the level of transcription in germinating oilseeds. After the discovery of AtACX3, the Arabidopsis acyl-CoA oxidase gene family now comprises four isozymes with substrate specificities that encompass the full range of acyl-CoA chain lengths that exist in vivo.
| Original language | English |
|---|---|
| Pages (from-to) | 34375-34381 |
| Number of pages | 7 |
| Journal | Journal of Biological Chemistry |
| Volume | 275 |
| Issue number | 44 |
| Publication status | Published - 3 Nov 2000 |
Keywords
- CARRIER PROTEIN THIOESTERASE
- PEROXISOMAL BETA-OXIDATION
- MALATE SYNTHASE GENE
- FATTY-ACIDS
- DEVELOPMENTAL REGULATION
- EXPRESSION
- PLANTS
- RECEPTOR
- BIOSYNTHESIS
- PURIFICATION