Arabidopsis CER1-LIKE1 Functions in a Cuticular Very-Long-Chain Alkane-Forming Complex

Abstract

Plant aerial organs are coated with cuticular waxes, a hydrophobic layer that primarily serves as a waterproofing barrier. Cuticular wax is a mixture of aliphatic very-long-chain molecules, ranging from 22 to 48 carbons, produced in the endoplasmic reticulum of epidermal cells. Among all wax components, alkanes represent up to 80% of total wax in Arabidopsis (Arabidopsis thaliana) leaves. Odd-numbered alkanes and their derivatives are produced through the alkane-forming pathway. Although the chemical reactions of this pathway have been well described, the enzymatic mechanisms catalyzing these reactions remain unclear. We previously showed that a complex made of Arabidopsis ECERIFERUM1 (CER1) and CER3 catalyzes the conversion of acyl-Coenzyme A's to alkanes with strict substrate specificity for compounds containing more than 29 carbons. To learn more about alkane biosynthesis in Arabidopsis, we characterized the biochemical specificity and physiological functions of a CER1 homolog, CER1-LIKE1. In a yeast strain engineered to produce very-long-chain fatty acids, CER1-LIKE1 interacted with CER3 and cytochrome B5 to form a functional complex leading to the production of alkanes that are of different chain lengths compared to that produced by CER1-containing complexes. Gene expression analysis showed that both CER1 and CER1-LIKE1 are differentially expressed in an organ-and tissue-specific manner. Moreover, the inactivation or overexpression of CER1-LIKE1 in Arabidopsis transgenic lines specifically impacted alkane biosynthesis and wax crystallization. Collectively, our study reports on the identification of a further plant alkane synthesis enzymatic component and supports a model in which several alkane-forming complexes with distinct chain-length specificities coexist in plants.

Proteome and transcriptome profile analysis reveals regulatory and stress-responsive networks in the russet fruit skin of sand pear

“…All these genes showed constant transcript levels but were strongly repressed at the protein level in russet fruit skin compared with green fruit skin of sand pear 23.1.199, EC: 1.1.1330, and EC: 1.3.1.93) inhibited the biosynthesis of long chain fatty acids, providing substrates for the biosynthesis of cutin, wax, and suberin. CER1 is a core component of the complex controlling very-longchain alkane synthesis [40][41][42] . CYP86A4 plays a key role as a cutin ω-hydroxylase in the biosynthesis of 16-hydroxypalmitate, 10,16-dihydroxypalmitate, and 1,16-hexadecanedioic acid 43 .…”

Epigenetic Activation of Enoyl-CoA Reductase By An Acetyltransferase Complex Triggers Wheat Wax Biosynthesis

“…It is well established in model plant Arabidopsis (Arabidopsis thaliana) that cuticular wax biosynthesis begins with the esterification of CoA to the plastid-derived C 16 and C 18 fatty acids by long-chain acyl-CoA synthetase proteins in the endoplasmic reticulum (ER), and the generated C 16 and C 18 acyl-CoAs are elongated to VLC acyl-CoAs under the action of the fatty acid elongase complex and ECERIFERUM2 proteins (Xia et al, 1996;Todd et al, 1999;Fiebig et al, 2000;Hooker et al, 2002;Schnurr et al, 2004;Zheng et al, 2005;Bach et al, 2008;Beaudoin et al, 2009;Lee et al, 2009;Lü et al, 2009;Weng et al, 2010;Haslam et al, 2012;Haslam and Kunst, 2013;Kim et al, 2013;Haslam et al, 2015). The elongated VLC acyl-CoAs are then modified into aldehydes, alkanes, secondary alcohols, and ketones by an alkane-forming pathway, or into primary alcohols and wax esters by an alcoholforming pathway (Aarts et al, 1995;Millar et al, 1999;Chen et al, 2003;Rowland et al, 2006Rowland et al, , 2007Greer et al, 2007;Bourdenx et al, 2011;Bernard et al, 2012;Yang et al, 2017;Pascal et al, 2019). As a core component of fatty acid elongase complex, enoyl-CoA reductase (ECR) catalyzes the final step in the biosynthesis of VLC acyl-CoAs (Zheng et al, 2005).…”

A combination of genome-wide association study and transcriptome analysis in leaf epidermis identifies candidate genes involved in cuticular wax biosynthesis in Brassica napus

“…In the decarbonylation pathway, VLC-acyl-CoAs are catalyzed into alkanes by an ER-localized CER1, CER3 and cytochrome B5 complex [33]. It was recently reported that the CER1 homolog, CER1-LIKE1, was also involved in alkane formation [44]. Subsequently, alkanes are oxidized into secondary alcohols and ketones by the midchain alkane hydroxylase 1 (MAH1) [34].…”