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The initial surface composition and topography modulate sphingomyelinase-driven sphingomyelin to ceramide conversion
Luisina De Tullio1, Bruno Maggio, Steffen Hartel
1Departamento de Química Biológica, Facultad de Ciencias Químicas - CONICET, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Ciudad Universitaria, X5000HUA Córdoba, República Argentina.
Cell Biochemistry and Biophysics
|July 27, 2007
Summary
Mixed lipid monolayers of sphingomyelin and ceramide affect sphingomyelin degradation by Bacillus cereus sphingomyelinase. Domain interfaces act as a supramolecular code, regulating enzyme efficiency and structuring lipid lattices.
Area of Science:
- Biochemistry
- Lipidomics
- Enzymology
Background:
- Sphingomyelin and ceramide form mixed monolayers with distinct phase behaviors.
- Bacillus cereus sphingomyelinase (BC-SMase) degrades sphingomyelin.
- The interplay between lipid composition and enzyme activity is not fully understood.
Purpose of the Study:
- To investigate how the initial composition and topography of sphingomyelin/ceramide mixed monolayers modulate BC-SMase activity.
- To elucidate the role of lipid domain interfaces in regulating enzyme catalysis.
Main Methods:
- Utilized mixed lipid monolayers of sphingomyelin and ceramide.
- Studied the effect of varying lipid compositions and resulting phase domain structures.
- Analyzed the degradation of sphingomyelin by BC-SMase.
Main Results:
- Changes in monolayer composition and topography significantly modulated sphingomyelin degradation by BC-SMase.
- The presence of lateral phase boundaries between condensed and expanded domains promoted precatalytic steps.
- Domain interface characteristics (undulation) acted as a supramolecular code regulating catalytic efficiency.
- BC-SMase activity influenced the long-range domain lattice structuring.
Conclusions:
- The structural organization of lipid monolayers, particularly domain interfaces, is a critical factor in regulating enzyme activity.
- Sphingomyelinase activity is modulated by the physical state and lateral organization of its lipid substrate.
- This study reveals a supramolecular code governing enzyme-substrate interactions at lipid interfaces.
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