Sphingomyelinase-Induced Domain Shape Relaxation Driven by Out-of-Equilibrium Changes of Composition

Fanani, ML; De Tullio, L; Hartel, S; Jara, J; Maggio, B

Abstract

Sphingomyelinase (SMase)-induced ceramide (Cer)-enriched domains in a lipid monolayer are shown to result from an out-of-equilibrium situation. This is induced by a change of composition caused by the enzymatic production of Cer in a sphingomyelin (SM) monolayer that leads to a fast SM/Cer demixing into a liquid-condensed (LC), Cer-enriched and a liquid-expanded, SM-enriched phases. The morphological evolution and kinetic dependence of Cer-enriched domains is studied under continuous observation by epifluorescence microscopy. Domain shape annealing is observed from branched to rounded shapes after SMase activity quenching by EDTA, with a decay halftime of ~10 min. An out-of-equilibrium fast domain growth is not the determinant factor for domain morphology. Domain shape rearrangement in nearly equilibrium conditions result from the counteraction of intradomain dipolar repulsion and line tension, according to McConnell's shape transition theory. Phase separation causes a transient compositional overshoot within the LC phase that implies an increased out-of-equilibrium enrichment of Cer into the LC domains. As a consequence, higher intradomain repulsion leads to transient branched structures that relax to rounded shapes by lowering the proportion of Cer in the domain to equilibrium values. The fast action of SMase can be taken as a compositional perturbation that brings about important consequences for the surface organization. © 2009 by the Biophysical Society.

Más información

Título según WOS: Sphingomyelinase-Induced Domain Shape Relaxation Driven by Out-of-Equilibrium Changes of Composition
Título según SCOPUS: Sphingomyelinase-induced domain shape relaxation driven by out-of-equilibrium changes of composition
Título de la Revista: BIOPHYSICAL JOURNAL
Volumen: 96
Número: 1
Editorial: Cell Press
Fecha de publicación: 2009
Página de inicio: 67
Página final: 76
Idioma: English
URL: http://linkinghub.elsevier.com/retrieve/pii/S0006349508000349
DOI:

10.1529/biophysj.108.141499

Notas: ISI, SCOPUS