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Membrane fusion induced by small molecules and ions.

Mondal Roy S, Sarkar M - J Lipids (2011)

Bottom Line: Small molecules/ions do not share this advantage.Here we intend to present, how a variety of small molecules/ions act as independent fusogens.The detailed mechanism of some are well understood but for many it is still an unanswered question.

View Article: PubMed Central - PubMed

Affiliation: Chemical Sciences Division, Saha Institute of Nuclear Physics, Sector 1, Block AF, Bidhannagar, Kolkata 700064, India.

ABSTRACT
Membrane fusion is a key event in many biological processes. These processes are controlled by various fusogenic agents of which proteins and peptides from the principal group. The fusion process is characterized by three major steps, namely, inter membrane contact, lipid mixing forming the intermediate step, pore opening and finally mixing of inner contents of the cells/vesicles. These steps are governed by energy barriers, which need to be overcome to complete fusion. Structural reorganization of big molecules like proteins/peptides, supplies the required driving force to overcome the energy barrier of the different intermediate steps. Small molecules/ions do not share this advantage. Hence fusion induced by small molecules/ions is expected to be different from that induced by proteins/peptides. Although several reviews exist on membrane fusion, no recent review is devoted solely to small moleculs/ions induced membrane fusion. Here we intend to present, how a variety of small molecules/ions act as independent fusogens. The detailed mechanism of some are well understood but for many it is still an unanswered question. Clearer understanding of how a particular small molecule can control fusion will open up a vista to use these moleucles instead of proteins/peptides to induce fusion both in vivo and in vitro fusion processes.

No MeSH data available.


Related in: MedlinePlus

Schematic diagram of the partition breakage model. The arrows in (1) show the La3+-induced lateral compression pressure of the membranes, and the green triangle in (2) shows the interstitial hydrocarbon region where free energy of chain packing is very large. Adapted from reference [64].
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fig5: Schematic diagram of the partition breakage model. The arrows in (1) show the La3+-induced lateral compression pressure of the membranes, and the green triangle in (2) shows the interstitial hydrocarbon region where free energy of chain packing is very large. Adapted from reference [64].

Mentions: A very new kind of mechanism, which is known as “partition breakage model” (Figure 5), where no stalk intermediate is formed, has been proposed in case of fusion of neutral GUVs induced by trivalent lanthanides, namely, La3+ or Gd3+ [64]. It has been observed that DOPE and dioleoylphosphatidylcholine (DOPC) mixed vesicle (30 DOPE : 70 DOPC) undergo membrane fusion on incorporation of 100 μM of La3+. The process of fusion has been shown by phase contrast imaging. After the merging of the GUVs, the density of the incorporated La3+ is increased in the outer lipid layer (facing the buffer). Due to this, the lateral compression pressure of the outer monolayer increases. The presence of DOPE in the GUVs favors the formation of HII (inverted hexagonal) phase, and La3+ stabilizes this HII phase hence, the area of the outer monolayer is decreased. Thus, the chain packing, mostly at the edge of partition membrane, is destabilized causing the breakage of the membrane at the edge. Then, the area of this breakage site increases, and finally the partition membrane gets ruptured. This is a unique example where membrane fusion occurs directly starting from merging of the vesicles without the formation of any hemifusion (stalk-like) intermediate. Moreover, the partition membrane that has separated from the GUVs during fusion forms a tiny SUV and resides inside the fused vesicle. That is why the area of the membrane of the fused vesicle will be decreased due to the loss of partition membrane.


Membrane fusion induced by small molecules and ions.

Mondal Roy S, Sarkar M - J Lipids (2011)

Schematic diagram of the partition breakage model. The arrows in (1) show the La3+-induced lateral compression pressure of the membranes, and the green triangle in (2) shows the interstitial hydrocarbon region where free energy of chain packing is very large. Adapted from reference [64].
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3108104&req=5

fig5: Schematic diagram of the partition breakage model. The arrows in (1) show the La3+-induced lateral compression pressure of the membranes, and the green triangle in (2) shows the interstitial hydrocarbon region where free energy of chain packing is very large. Adapted from reference [64].
Mentions: A very new kind of mechanism, which is known as “partition breakage model” (Figure 5), where no stalk intermediate is formed, has been proposed in case of fusion of neutral GUVs induced by trivalent lanthanides, namely, La3+ or Gd3+ [64]. It has been observed that DOPE and dioleoylphosphatidylcholine (DOPC) mixed vesicle (30 DOPE : 70 DOPC) undergo membrane fusion on incorporation of 100 μM of La3+. The process of fusion has been shown by phase contrast imaging. After the merging of the GUVs, the density of the incorporated La3+ is increased in the outer lipid layer (facing the buffer). Due to this, the lateral compression pressure of the outer monolayer increases. The presence of DOPE in the GUVs favors the formation of HII (inverted hexagonal) phase, and La3+ stabilizes this HII phase hence, the area of the outer monolayer is decreased. Thus, the chain packing, mostly at the edge of partition membrane, is destabilized causing the breakage of the membrane at the edge. Then, the area of this breakage site increases, and finally the partition membrane gets ruptured. This is a unique example where membrane fusion occurs directly starting from merging of the vesicles without the formation of any hemifusion (stalk-like) intermediate. Moreover, the partition membrane that has separated from the GUVs during fusion forms a tiny SUV and resides inside the fused vesicle. That is why the area of the membrane of the fused vesicle will be decreased due to the loss of partition membrane.

Bottom Line: Small molecules/ions do not share this advantage.Here we intend to present, how a variety of small molecules/ions act as independent fusogens.The detailed mechanism of some are well understood but for many it is still an unanswered question.

View Article: PubMed Central - PubMed

Affiliation: Chemical Sciences Division, Saha Institute of Nuclear Physics, Sector 1, Block AF, Bidhannagar, Kolkata 700064, India.

ABSTRACT
Membrane fusion is a key event in many biological processes. These processes are controlled by various fusogenic agents of which proteins and peptides from the principal group. The fusion process is characterized by three major steps, namely, inter membrane contact, lipid mixing forming the intermediate step, pore opening and finally mixing of inner contents of the cells/vesicles. These steps are governed by energy barriers, which need to be overcome to complete fusion. Structural reorganization of big molecules like proteins/peptides, supplies the required driving force to overcome the energy barrier of the different intermediate steps. Small molecules/ions do not share this advantage. Hence fusion induced by small molecules/ions is expected to be different from that induced by proteins/peptides. Although several reviews exist on membrane fusion, no recent review is devoted solely to small moleculs/ions induced membrane fusion. Here we intend to present, how a variety of small molecules/ions act as independent fusogens. The detailed mechanism of some are well understood but for many it is still an unanswered question. Clearer understanding of how a particular small molecule can control fusion will open up a vista to use these moleucles instead of proteins/peptides to induce fusion both in vivo and in vitro fusion processes.

No MeSH data available.


Related in: MedlinePlus