RESUMEN
Congenital myasthenic syndromes (CMS) are heterogeneous disorders in which the safety margin of neuromuscular transmission is impaired by one or more specific mechanisms. Since the advent of next-generation sequencing methods, the discovery of novel CMS targets and phenotypes has proceeded at an accelerated rate. Here, we review the current classification of CMS and describe our findings in five of these targets identified and investigated in our laboratory in the past 5 years. Defects in LRP4 hinder synaptic development and maintenance; the defects in PREPL are predicted to diminish filling of the synaptic vesicle with acetylcholine; and defects in SNAP25, Munc13-1, and synaptotbrevin-1 impede synaptic vesicle exocytosis.
Asunto(s)
Síndromes Miasténicos Congénitos/genética , Síndromes Miasténicos Congénitos/patología , Unión Neuromuscular/patología , Transmisión Sináptica/fisiología , Acetilcolina/metabolismo , Humanos , Proteínas Relacionadas con Receptor de LDL/genética , Proteínas del Tejido Nervioso/genética , Prolil Oligopeptidasas , Proteínas R-SNARE/genética , Serina Endopeptidasas/genética , Proteína 25 Asociada a Sinaptosomas/genéticaRESUMEN
DHHC enzymes catalyze palmitoylation, a major post-translational modification that regulates a number of key cellular processes. There are up to 24 DHHCs in mammals and hundreds of substrate proteins that get palmitoylated. However, how DHHC enzymes engage with their substrates is still poorly understood. There is currently no structural information about the interaction between any DHHC enzyme and protein substrates. In this study we have investigated the structural and thermodynamic bases of interaction between the ankyrin repeat domain of human DHHC17 (ANK17) and Snap25b. We solved a high-resolution crystal structure of the complex between ANK17 and a peptide fragment of Snap25b. Through structure-guided mutagenesis, we discovered key residues in DHHC17 that are critically important for interaction with Snap25b. We further extended our finding by showing that the same residues are also crucial for the interaction of DHHC17 with Huntingtin, one of its most physiologically relevant substrates.
