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From vesicles to protocells: the roles of amphiphilic molecules.

Sakuma Y, Imai M - Life (Basel) (2015)

Bottom Line: It is very challenging to construct protocells from molecular assemblies.Soft matter physics will play an important role in the development of vesicles that have these functions.Here, we show that simple binary phospholipid vesicles have the potential to reproduce the relevant functions of adhesion, pore formation and self-reproduction of vesicles, by coupling the lipid geometries (spontaneous curvatures) and the phase separation.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Tohoku University, Aoba, Sendai 980-8578, Japan. sakuma@bio.phys.tohoku.ac.jp.

ABSTRACT
It is very challenging to construct protocells from molecular assemblies. An important step in this challenge is the achievement of vesicle dynamics that are relevant to cellular functions, such as membrane trafficking and self-reproduction, using amphiphilic molecules. Soft matter physics will play an important role in the development of vesicles that have these functions. Here, we show that simple binary phospholipid vesicles have the potential to reproduce the relevant functions of adhesion, pore formation and self-reproduction of vesicles, by coupling the lipid geometries (spontaneous curvatures) and the phase separation. This achievement will elucidate the pathway from molecular assembly to cellular life.

No MeSH data available.


Related in: MedlinePlus

Schematic representations of cone-, cylinder- and inverse-cone-shaped lipids.
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life-05-00651-f007: Schematic representations of cone-, cylinder- and inverse-cone-shaped lipids.

Mentions: In present cellular life, the deformations relevant to biological functions are controlled by specific proteins. The proteins contribute to the local membrane curvatures by interacting with lipids [44]. These sophisticated proteins are, however, the result of evolution over a period of several billion years. In the early stage of the protocell era, amphiphilic molecules may have played the roles of the proteins. In this review, we demonstrate how amphiphilic molecules can influence the local membrane curvature relevant to cellular life. The key concept is a coupling between the molecular shape and the distribution of amphiphilic molecules. From a geometrical point of view, the shape of amphiphilic molecules can be classified into three types (spontaneous curvatures): a cone, a cylinder and an inverse-cone shape (Figure 7) [3]. If the amphiphilic molecule has small hydrocarbon chains and a large headgroup (e.g., the cone shape), the monolayer has a tendency to bend toward the side of the tail. Similarly, an amphiphilic molecule having bulky hydrocarbon chains and a small headgroup (e.g., the inverse-cone shape) tends to bend the monolayer toward the side of the headgroups. An amphiphilic molecule that prefers to form a flat monolayer is referred to as a cylinder-shaped molecule. In the case of the flat bilayer, such geometrical preference is cancelled due to the symmetry of the bilayer. In the curved bilayer, however, the asymmetric amphiphilic molecules prefer to partition in a leaflet having the same bending direction. For example, inverse-cone shaped lipids prefer to partition in the inner leaflet of a spherical vesicle, and the lipids in the outer leaflet are highly frustrated. This geometrical frustration causes shape deformations.


From vesicles to protocells: the roles of amphiphilic molecules.

Sakuma Y, Imai M - Life (Basel) (2015)

Schematic representations of cone-, cylinder- and inverse-cone-shaped lipids.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4390873&req=5

life-05-00651-f007: Schematic representations of cone-, cylinder- and inverse-cone-shaped lipids.
Mentions: In present cellular life, the deformations relevant to biological functions are controlled by specific proteins. The proteins contribute to the local membrane curvatures by interacting with lipids [44]. These sophisticated proteins are, however, the result of evolution over a period of several billion years. In the early stage of the protocell era, amphiphilic molecules may have played the roles of the proteins. In this review, we demonstrate how amphiphilic molecules can influence the local membrane curvature relevant to cellular life. The key concept is a coupling between the molecular shape and the distribution of amphiphilic molecules. From a geometrical point of view, the shape of amphiphilic molecules can be classified into three types (spontaneous curvatures): a cone, a cylinder and an inverse-cone shape (Figure 7) [3]. If the amphiphilic molecule has small hydrocarbon chains and a large headgroup (e.g., the cone shape), the monolayer has a tendency to bend toward the side of the tail. Similarly, an amphiphilic molecule having bulky hydrocarbon chains and a small headgroup (e.g., the inverse-cone shape) tends to bend the monolayer toward the side of the headgroups. An amphiphilic molecule that prefers to form a flat monolayer is referred to as a cylinder-shaped molecule. In the case of the flat bilayer, such geometrical preference is cancelled due to the symmetry of the bilayer. In the curved bilayer, however, the asymmetric amphiphilic molecules prefer to partition in a leaflet having the same bending direction. For example, inverse-cone shaped lipids prefer to partition in the inner leaflet of a spherical vesicle, and the lipids in the outer leaflet are highly frustrated. This geometrical frustration causes shape deformations.

Bottom Line: It is very challenging to construct protocells from molecular assemblies.Soft matter physics will play an important role in the development of vesicles that have these functions.Here, we show that simple binary phospholipid vesicles have the potential to reproduce the relevant functions of adhesion, pore formation and self-reproduction of vesicles, by coupling the lipid geometries (spontaneous curvatures) and the phase separation.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Tohoku University, Aoba, Sendai 980-8578, Japan. sakuma@bio.phys.tohoku.ac.jp.

ABSTRACT
It is very challenging to construct protocells from molecular assemblies. An important step in this challenge is the achievement of vesicle dynamics that are relevant to cellular functions, such as membrane trafficking and self-reproduction, using amphiphilic molecules. Soft matter physics will play an important role in the development of vesicles that have these functions. Here, we show that simple binary phospholipid vesicles have the potential to reproduce the relevant functions of adhesion, pore formation and self-reproduction of vesicles, by coupling the lipid geometries (spontaneous curvatures) and the phase separation. This achievement will elucidate the pathway from molecular assembly to cellular life.

No MeSH data available.


Related in: MedlinePlus