Sphingomyelinase D activity in model membranes: structural effects of in situ generation of ceramide-1-phosphate

Roberto Stock, Jonathan R. Brewer, Kerstin Wagner, Blanca Ramos-Cerrillo, Lars Duelund, Kit Drescher Jernshøj, Lars Folke Olsen, Luis Bagatolli

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The toxicity of Loxosceles spider venom has been attributed to a rare enzyme, sphingomyelinase D, which transforms sphingomyelin to ceramide-1-phosphate. The bases of its inflammatory and dermonecrotic activity, however, remain unclear. In this work the effects of ceramide-1-phosphate on model membranes were studied both by in situ generation of this lipid using a recombinant sphingomyelinase D from the spider Loxosceles laeta and by pre-mixing it with sphingomyelin and cholesterol. The systems of choice were large unilamellar vesicles for bulk studies (enzyme kinetics, fluorescence spectroscopy and dynamic light scattering) and giant unilamellar vesicles for fluorescence microscopy examination using a variety of fluorescent probes. The influence of membrane lateral structure on the kinetics of enzyme activity and the consequences of enzyme activity on the structure of target membranes containing sphingomyelin were examined. The findings indicate that: 1) ceramide-1-phosphate (particularly lauroyl ceramide-1-phosphate) can be incorporated into sphingomyelin bilayers in a concentration-dependent manner and generates coexistence of liquid disordered/solid ordered domains, 2) the activity of sphingomyelinase D is clearly influenced by the supramolecular organization of its substrate in membranes and, 3) in situ ceramide-1-phosphate generation by enzymatic activity profoundly alters the lateral structure and morphology of the target membranes.
Original languageEnglish
JournalPLOS ONE
Volume7
Issue number4
Pages (from-to)1-15 (e-36003)
Number of pages15
ISSN1932-6203
Publication statusPublished - 25. Apr 2012

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