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Publication Detail
Novel HSAN1 Mutation in Serine Palmitoyltransferase Resides at a Putative Phosphorylation Site That Is Involved in Regulating Substrate Specificity
  • Publication Type:
    Journal article
  • Publication Sub Type:
    Journal Article
  • Authors:
    Ernst D, Murphy SM, Sathiyanadan K, Wei Y, Othman A, Laurá M, Liu YT, Penno A, Blake J, Donaghy M, Houlden H, Reilly MM, Hornemann T
  • Publication date:
    01/01/2015
  • Pagination:
    47, 57
  • Journal:
    NeuroMolecular Medicine
  • Volume:
    17
  • Issue:
    1
  • Status:
    Published
  • Print ISSN:
    1535-1084
Abstract
© 2015, The Author(s). 1-Deoxysphingolipids (1-deoxySL) are atypical sphingolipids that are formed by the enzyme serine palmitoyltransferase (SPT) due to a promiscuous use of l-alanine over its canonical substrate l-serine. Several mutations in SPT are associated with the hereditary sensory and autonomic neuropathy type I (HSAN1). The current hypothesis is that these mutations induce a permanent shift in the affinity from l-serine toward l-alanine which results in a pathologically increased 1-deoxySL formation in HSAN1 patients. Also, wild-type SPT forms 1-deoxySL under certain conditions, and elevated levels were found in individuals with the metabolic syndrome and diabetes. However, the molecular mechanisms which control the substrate shift of the wild-type enzyme are not understood. Here, we report a novel SPTLC2–S384F variant in two unrelated HSAN1 families. Affected patients showed elevated plasma 1-deoxySL levels and expression of the S384F mutant in HEK293 cells increased 1-deoxySL formation. Previously, S384 has been reported as one of the two (S384 and Y387) putative phosphorylation sites in SPTLC2. The phosphorylation of wild-type SPTLC2 was confirmed by isoelectric focusing. The impact of an S384 phosphorylation on SPT activity was tested by creating mutants mimicking either a constitutively phosphorylated (S384D, S384E) or non-phosphorylated (S384A, Y387F, Y387F+S384A) protein. The S384D but not the S384E variant was associated with increased 1-deoxySL formation. The other mutations had no influence on activity and substrate affinity. In summary, our data show that S384F is a novel mutation in HSAN1 and that the substrate specificity of wild-type SPT might by dynamically regulated by a phosphorylation at this position.
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Department of Neuromuscular Diseases
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Department of Neuromuscular Diseases
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