Acyl-CoA oxidase complexes control the chemical message produced by Caenorhabditis elegans

Abstract

Caenorhabditis elegans uses ascaroside pheromones to induce development of the stress-resistant dauer larval stage and to coordinate various behaviors. Peroxisomal β-oxidation cycles are required for the biosynthesis of the fatty acid-derived side chains of the ascarosides. Here we show that three acyl-CoA oxidases, which catalyze the first step in these β-oxidation cycles, form different protein homo-and heterodimers with distinct substrate preferences. Mutations in the acyl-CoA oxidase genes acox-1, -2, and -3 led to specific defects in ascaroside production. When the acyl-CoA oxidases were expressed alone or in pairs and purified, the resulting acyl-CoA oxidase homo-and heterodimers displayed different sidechain length preferences in an in vitro activity assay. Specifically, an ACOX-1 homodimer controls the production of ascarosides with side chains with nine or fewer carbons, an ACOX-1/ACOX-3 heterodimer controls the production of those with side chains with seven or fewer carbons, and an ACOX-2 homodimer controls the production of those with ω-side chains with less than five carbons. Our results support a biosynthetic model in which β-oxidation enzymes act directly on the CoA-thioesters of ascaroside biosynthetic precursors. Furthermore, we identify environmental conditions, including high temperature and low food availability, that induce the expression of acox-2 and/or acox-3 and lead to corresponding changes in ascaroside production. Thus, our work uncovers an important mechanism by which C. elegans increases the production of the most potent dauer pheromones, those with the shortest side chains, under specific environmental conditions. dauer | pheromone | ascaroside | beta-oxidation | acyl-CoA oxidase

Structural characterization of acyl-CoA oxidases reveals a direct link between pheromone biosynthesis and metabolic state in Caenorhabditis elegans

“…In contrast, an ACOX-1/ACOX-3 heterodimer is specific to an (ω-1)-ascaroside substrate with a 7-carbon side chain, and an ACOX-2 homodimer is specific to an ω-ascaroside substrate with a 5-carbon side chain (7). By regulating the expression of these ACOXs, C. elegans can control the production of specific ascarosides (7). For example, C. elegans regulates the expression of ACOX-2 to influence the production of an ascaroside with a short ω-side chain, the dauer pheromone asc-ωC3 (C3; ascr#5), and it regulates the expression of ACOX-3 to influence the production of ascarosides with shorter (ω-1)-side chains, such as the dauer pheromone asc-C6-MK (C6; ascr#2) (SI Appendix, Figs.…”

“…specific ascaroside-CoA substrates, including an (ω-1)-ascaroside with a 9-carbon side chain (7). In contrast, an ACOX-1/ACOX-3 heterodimer is specific to an (ω-1)-ascaroside substrate with a 7-carbon side chain, and an ACOX-2 homodimer is specific to an ω-ascaroside substrate with a 5-carbon side chain (7).…”

“…In contrast, an ACOX-1/ACOX-3 heterodimer is specific to an (ω-1)-ascaroside substrate with a 7-carbon side chain, and an ACOX-2 homodimer is specific to an ω-ascaroside substrate with a 5-carbon side chain (7). By regulating the expression of these ACOXs, C. elegans can control the production of specific ascarosides (7).…”

“…In the nematode C. elegans, peroxisomal β-oxidation not only functions in primary metabolism, but also has been coopted in the biosynthesis of a class of secondary metabolites known as the ascarosides (3)(4)(5)(6)(7). These ascarosides, which are secreted as pheromones, are derivatives of the 3,6-dideoxy-L-sugar ascarylose and are modified with fatty acid-derived side chains of various lengths (SI Appendix, Fig.…”

“…S1 A and B) (8)(9)(10)(11)(12)(13). C. elegans makes ascarosides with long side chains and then shortens these side chains through β-oxidation to make the short-chain ascaroside pheromones (3)(4)(5)(6)(7). These pheromones enable C. elegans to coordinate the development and behavior of the population.…”