The very-long-chain hydroxy fatty acyl-CoA dehydratase PASTICCINO2 is essential and limiting for plant development

Abstract

Very-long-chain fatty acids (VLCFAs) are synthesized as acyl-CoAs by the endoplasmic reticulum-localized elongase multiprotein complex. Two Arabidopsis genes are putative homologues of the recently identified yeast 3-hydroxy-acyl-CoA dehydratase (PHS1), the third enzyme of the elongase complex. We showed that Arabidopsis PASTICCINO2 (PAS2) was able to restore phs1 cytokinesis defects and sphingolipid long chain base overaccumulation. Conversely, the expression of PHS1 was able to complement the developmental defects and the accumulation of long chain bases of the pas2-1 mutant. The pas2-1 mutant was characterized by a general reduction of VLCFA pools in seed storage triacylglycerols, cuticular waxes, and complex sphingolipids. Most strikingly, the defective elongation cycle resulted in the accumulation of 3-hydroxy-acyl-CoA intermediates, indicating premature termination of fatty acid elongation and confirming the role of PAS2 in this process. We demonstrated by in vivo bimolecular fluorescence complementation that PAS2 was specifically associated in the endoplasmic reticulum with the enoyl-CoA reductase CER10, the fourth enzyme of the elongase complex. Finally, complete loss of PAS2 function is embryo lethal, and the ectopic expression of PHS1 led to enhanced levels of VLCFAs associated with severe developmental defects. Altogether these results demonstrate that the plant 3-hydroxy-acyl-CoA dehydratase PASTICCINO2 is an essential and limiting enzyme in VLCFA synthesis but also that PAS2-derived VLCFA homeostasis is required for specific developmental processes. cuticular wax ͉ elongase ͉ sphingolipid ͉ triacylglycerol ͉ leaf development

Isolation and characterization of Arabidopsis mutants with enhanced tolerance to oxidative stress

“…Sphingolipids are essential regulators not only of cell death, but also of development in both animal and plant cells (Teufel et al 2009;Chen et al 2008). This notion is supported by the various developmental defects in mutants with compromised very long-chain fatty acids that are components of sphingolipids and in mutants with impaired hydroxylation of long-chain bases (Bach et al 2008;Zheng et al 2005;Chen et al 2008). It could be that all mutants, being in loh2 background that lacks certain complex sphingolipids, are unable to proceed into mature plants when AAL toxin is present.…”

Control of Cell Proliferation, Organ Growth, and DNA Damage Response Operate Independently of Dephosphorylation of the Arabidopsis Cdk1 Homolog CDKA;1

“…If the mutant phenotype of pas2/pep were due to uninhibited CDKA;1, the phenotype of DE plants should be epistatic, but the phenotype of pas2/pep-DE was additive (i.e., plants were tiny, yet overproliferating) ( Figures 1B and 1C), corroborating that PAS2/PEP functions in parallel to CDKA;1. Consistent with these observations, it was recently reported that PAS2/PEP is involved in fatty acid metabolism and can function as a 3-hydroxy-acylCoA dehydratase (Bach et al, 2008). The DNA Damage Response Pathway in Arabidopsis Does Not Depend on P-Loop Phosphorylation P-loop phosphorylation of CDKs was found to be especially crucial in metazoans when the nuclear DNA is damaged (Yata and Esashi, 2009) in order to prevent mitosis of abnormal cells.…”

The Formation and Function of Plant Cuticles

“…In Arabidopsis, 21 genes are predicted to encode b-ketoacyl-CoA synthase, and for wax biosynthesis, the most important gene, based on the mutant phenotype, is CER6 (Fiebig et al, 2000). Genes encoding the remaining subunits of the FAE complex, represented by KCR1, PAS2, and CER10, respectively, are less redundant, and their pleiotropic mutant phenotypes underscore the shared importance of the FAE in generating VLCFA precursors for sphingolipid biosynthesis (Zheng et al, 2005;Bach et al, 2008;Beaudoin et al, 2009). An additional family of proteins, composed of CER2, CER26, and CER26-like, appears to be required for the elongation of fatty acids to lengths greater than 28C Pascal et al, 2013).…”