A systematic analysis of protein palmitoylation in Caenorhabditis elegans

Abstract

BackgroundPalmitoylation is a reversible post-translational protein modification which involves the addition of palmitate to cysteine residues. Palmitoylation is catalysed by the DHHC family of palmitoyl-acyl transferases (PATs) and reversibility is conferred by palmitoyl-protein thioesterases (PPTs). Mutations in genes encoding both classes of enzymes are associated with human diseases, notably neurological disorders, underlining their importance. Despite the pivotal role of yeast studies in discovering PATs, palmitoylation has not been studied in the key animal model Caenorhabditis elegans.ResultsAnalysis of the C. elegans genome identified fifteen PATs, using the DHHC cysteine-rich domain, and two PPTs, by homology. The twelve uncategorised PATs were officially named using a dhhc-x system. Genomic data on these palmitoylation enzymes and those in yeast, Drosophila and humans was collated and analysed to predict properties and relationships in C. elegans. All available C. elegans strains containing a mutation in a palmitoylation enzyme were analysed and a complete library of RNA interference (RNAi) feeding plasmids against PAT or PPT genes was generated. To test for possible redundancy, double RNAi was performed against selected closely related PATs and both PPTs. Animals were screened for phenotypes including size, longevity and sensory and motor neuronal functions. Although some significant differences were observed with individual mutants or RNAi treatment, in general there was little impact on these phenotypes, suggesting that genetic buffering exists within the palmitoylation network in worms.ConclusionsThis study reports the first characterisation of palmitoylation in C. elegans using both in silico and in vivo approaches, and opens up this key model organism for further detailed study of palmitoylation in future.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-841) contains supplementary material, which is available to authorized users.

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“…These studies indicated that DHHC sequence is critical for the PAT activity of Akr1 and Erf2, initially suggesting that DHHC family proteins are PATs. To date, a number of DHHC family proteins have been predicted in various species, including the yeast Saccharomyces cerevisiae (7 genes) [57], Caenorhabditis elegans (15 genes) [59], the fruit fly Drosophila (22 genes) [60], the mouse and human (23 genes) [9,32], and even the plant Arabidopsis (24 genes) [61,62]. Among these DHHC proteins, 6 (Akr1, Erf2, Swf1, Pfa3, Pfa4 and Pfa5) in yeast [47,52,57,[63][64][65][66], 20 (DHHC19, DHHC1121) in mammals [25,42,[67][68][69], and 2 (TIP1 and PAT10) in plants have already been confirmed as PATs [70,71].…”

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