Transient domain formation in membrane-bound organelles undergoing maturation

Abstract

The membrane components of cellular organelles have been shown to segregate into domains as the result of biochemical maturation. We propose that the dynamical competition between maturation and lateral segregation of membrane components regulates domain formation. We study a twocomponent fluid membrane in which enzymatic reaction irreversibly converts one component into another, and phase separation triggers the formation of transient membrane domains. The maximum domains size is shown to depend on the maturation rate as a power-law similar to the one observed for domain growth with time in the absence of maturation, despite this time dependence not being verified in the case of irreversible maturation. This control of domain size by enzymatic activity could play a critical role in intra-organelle dynamics.

Expression, sorting, and segregation of Golgi proteins during germ cell differentiation in the testis

“…The maturation model of Golgi stack anterograde progression has been considered as the model for acrosome formation ( Hermo et al ., 2010a ). However, based on the strict segregation of Golgi markers seen here, alternative models for Golgi traffic and biogenesis cannot be ruled out ( Patterson et al ., 2008 ; Dmitrieff and Sens, 2013 ; Lavieu et al ., 2013 , 2014 ).…”

Modeling the interplay between protein and lipid aggregation in supported membranes

“…Overall, phase segregation in lipid membranes has been shown to share the characteristics of two-dimensional systems (Honerkamp-Smith et al, 2008;Fan et al, 2010Fan et al, , 2008. Coarser descriptions of the lipid membrane composition as a continuous field over the membrane surface (Reigada et al, 2008;Dmitrieff and Sens, 2013), without individual representation of lipid molecules, provide a very useful view for studying processes at the mesoscopic scale. This is the important level of description in our case, since the composition of the lipid bilayer is only relevant when averaged over the size of the protein monomers.…”

“…the phase rich in the maleimide containing lipid). A mean field free energy functional F[ (R)] could be constructed adding to (2) an entropic contribution, proportional to kT, and it could be used in Cahn-Hillard or Ginzburg-Landau models (Reigada et al, 2008;Dmitrieff and Sens, 2013) for the equilibrium phase diagram and the phase transition dynamics of the systems. Since we aim to analyze the collective effects of the lipid-protein structures, we have followed a different approach, running in parallel the MC simulations for the proteins and for the lipid bilayer.…”

“…The resulting structural organization of the complex lipid-protein structure is then the balance of the interplay between these two trends. Biomembranes have a high protein content, so it is important to include their contribution in physical models that aim to explain their behavior (Jacobson et al, 2007;Yethiraj and Weisshaar, 2007;Fischer and Vink, 2011;Fischer et al, 2012;Dmitrieff and Sens, 2013).…”

Sensing Size through Clustering in Non-Equilibrium Membranes and the Control of Membrane-Bound Enzymatic Reactions

“…The compositional diversity of cell membranes [ 19 , 20 ] could be partly responsible for this difference but it is important to note that cell membranes are inherently out-of-equilibrium systems, experiencing continuous fluxes of matter and energy that may either drive or hinder spatial segregation. These fluxes might include the active transport of membrane proteins by the cytoskeleton [ 21 ], the recycling of membrane components by exocytosis and endocytosis [ 22 ] or the activation/inactivation cycle of GTPases such as Rab proteins [ 23 ].…”