Dataset Information

Spontaneous Membrane Nanodomain Formation in the Absence or Presence of the Neurotransmitter Serotonin.

ABSTRACT: Detailed knowledge on the formation of biomembrane domains, their structure, composition, and physical characteristics is scarce. Despite its frequently discussed importance in signaling, e.g., in obtaining localized non-homogeneous receptor compositions in the plasma membrane, the nanometer size as well as the dynamic and transient nature of domains impede their experimental characterization. In turn, atomistic molecular dynamics (MD) simulations combine both, high spatial and high temporal resolution. Here, using microsecond atomistic MD simulations, we characterize the spontaneous and unbiased formation of nano-domains in a plasma membrane model containing phosphatidylcholine (POPC), palmitoyl-sphingomyelin (PSM), and cholesterol (Chol) in the presence or absence of the neurotransmitter serotonin at different temperatures. In the ternary mixture, highly ordered and highly disordered domains of similar composition coexist at 303 K. The distinction of domains by lipid acyl chain order gets lost at lower temperatures of 298 and 294 K, suggesting a phase transition at ambient temperature. By comparison of domain ordering and composition, we demonstrate how the domain-specific binding of the neurotransmitter serotonin results in a modified domain lipid composition and a substantial downward shift of the phase transition temperature. Our simulations thus suggest a novel mode of action of neurotransmitters possibly of importance in neuronal signal transmission.

SUBMITTER: Bochicchio A

PROVIDER: S-EPMC7734319 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Spontaneous Membrane Nanodomain Formation in the Absence or Presence of the Neurotransmitter Serotonin.

Bochicchio Anna A Brandner Astrid F AF Engberg Oskar O Huster Daniel D Böckmann Rainer A RA

Frontiers in cell and developmental biology 20201130

Detailed knowledge on the formation of biomembrane domains, their structure, composition, and physical characteristics is scarce. Despite its frequently discussed importance in signaling, e.g., in obtaining localized non-homogeneous receptor compositions in the plasma membrane, the nanometer size as well as the dynamic and transient nature of domains impede their experimental characterization. In turn, atomistic molecular dynamics (MD) simulations combine both, high spatial and high temporal res ...[more]

PMID: 33330494

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Project description:Sphingomyelin is an abundant lipid in some cellular membrane domains, such as lipid rafts. Hydrogen bonding and hydrophobic interactions of the lipid with surrounding components such as neighboring sphingomyelin and cholesterol (Cho) are widely considered to stabilize the raft-like liquid-ordered (Lo) domains in membrane bilayers. However, details of their interactions responsible for the formation of Lo domains remain largely unknown. In this study, the enantiomer of stearoyl sphingomyelin (ent-SSM) was prepared, and its physicochemical properties were compared with the natural SSM and the diastereomer of SSM to examine possible stereoselective lipid-lipid interactions. Interestingly, differential scanning calorimetry experiments demonstrated that palmitoyl sphingomyelin, with natural stereochemistry, exhibited higher miscibility with SSM bilayers than with ent-SSM bilayers, indicating that the homophilic sphingomyelin interactions occurred in a stereoselective manner. Solid-state 2H NMR revealed that Cho elicited its ordering effect very similarly on SSM and ent-SSM (and even on the diastereomer of SSM), suggesting that SSM-Cho interactions are not significantly affected by stereospecific hydrogen bonding. SSM and ent-SSM formed gel-like domains with very similar lateral packing in SSM/Cho/palmitoyloleoyl phosphatidylcholine membranes, as shown by fluorescence lifetime experiments. This observation can be explained by a homophilic hydrogen-bond network, which was largely responsible for the formation of gel-like nanodomains of SSMs (or ent-SSM). Our previous study revealed that Cho-poor gel-like domains contributed significantly to the formation of an Lo phase in sphingomyelin/Cho membranes. The results of the study presented here further show that SSM-SSM interactions occur near the headgroup region, whereas hydrophobic SSM-Cho interactions appeared important in the bilayer interior for Lo domain formation. The homophilic interactions of sphingomyelins could be mainly responsible for the formation of the domains of nanometer size, which may correspond to the small sphingomyelin/Cho-based rafts that temporally occur in biological membranes.

Dataset Information

Spontaneous Membrane Nanodomain Formation in the Absence or Presence of the Neurotransmitter Serotonin.

Publications

Spontaneous Membrane Nanodomain Formation in the Absence or Presence of the Neurotransmitter Serotonin.

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