A cluster of palmitoylated cysteines are essential for aggregation of cysteine-string protein mutants that cause neuronal ceroid lipofuscinosis

Diez Ardanuy, Cinta and Greaves, Jennifer and Munro, Kevin R. and Tomkinson, Nicholas C.O. and Chamberlain, Luke H. (2017) A cluster of palmitoylated cysteines are essential for aggregation of cysteine-string protein mutants that cause neuronal ceroid lipofuscinosis. Scientific Reports. ISSN 2045-2322

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    Abstract

    Autosomal-dominant adult-onset neuronal cero id lipofuscinosis (ANCL) is caused by mutation of the DNAJC5 gene encoding cysteine string protein alpha (CSP α ). The disease- causing mutations, which result in substituti on of leucine-115 with an arginine (L115R) or deletion of the neig hbouring leucine-116 ( Δ L116) in the cysteine-string domain cause CSP α to form high molecular weight SDS-resistant aggregates, which are also present in post- mortem brain tissue from patients. Formation and stability of these mutant aggregates is linked to palmitoylation of the cysteine-str ing domain, however the regions of the mutant proteins that drive aggregatio n have not been determined. The importance of specific residues in the cysteine-string domain was in vestigated, revealing that a central core of palmitoylated cysteines is essential for aggregation of ANCL CSP α mutants. Interestingly, palmitoylated monomers of ANCL CSP α mutants were shown to be short-lived compared with wild-type CSP α, suggesting that the mutants eith er have a faster rate of depalmitoylation or that they are consumed in a time-dependent manner into high molecular weight aggregates. These findings provide new insight into the features of CSP α that promote aggregation in the presence of L115R/ Δ L116 mutations and reveal a change in the lifetime of palmitoyla ted monomers of the mutant proteins.