Oligomerization of Cysteine String Protein alpha mutants causing adult neuronal ceroid lipofuscinosis.

ABSTRACT: Cysteine String Protein alpha (CSP?) is a palmitoylated, synaptic vesicle co-chaperone that is essential for neuroprotection. Two mutations in CSP? - L115R and L116? - cause adult neuronal ceroid lipofuscinosis (ANCL), a dominantly-inherited neurodegenerative disease. To elucidate the pathogenesis of ANCL, the intrinsic biochemical properties of human wildtype (WT) and disease mutant CSP? were examined. Mutant proteins purified from Escherichia coli exhibited high potency to oligomerize in a concentration, temperature, and time dependent manner, with L115R possessing the greatest potency. When freshly purified, ANCL mutant proteins displayed normal co-chaperone activity and substrate recognition similar to WT. However, co-chaperone activity was impaired for both CSP? mutants upon oligomerization. When WT and mutant CSP? were mixed together they co-oligomerized leading to an overall decrease of co-chaperone activity. The oligomerization properties of ANCL mutants were faithfully replicated in HEK 293T cells. Interestingly, the oligomers were covalently tagged by ubiquitination instead of palmitoylation. Taken together, ANCL mutations result in both a gain and partial loss-of-function.

SUBMITTER: Zhang YQ 

PROVIDER: S-EPMC4188699 | biostudies-other | 2014 Nov

REPOSITORIES: biostudies-other