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Physical Routes to Primitive Cells: An Experimental Model Based on the Spontaneous Entrapment of Enzymes inside Micrometer-Sized Liposomes.

D'Aguanno E, Altamura E, Mavelli F, Fahr A, Stano P, Luisi PL - Life (Basel) (2015)

Bottom Line: We have reported that proteins and ribosomes can be encapsulated very efficiently, against statistical expectations, inside a small number of liposomes.Moreover the transcription-translation mixture, which realistically mimics a sort of minimal metabolic network, can be functionally reconstituted in liposomes owing to a self-concentration mechanism.Here we firstly summarize the recent advancements in this research line, highlighting how these results open a new vista on the phenomena that could have been important for the formation of functional primitive cells.

View Article: PubMed Central - PubMed

Affiliation: Science Department, Roma Tre University, Viale G. Marconi 446, I-00146 Rome, Italy. Alfred.Fahr@uni-jena.de.

ABSTRACT
How did primitive living cells originate? The formation of early cells, which were probably solute-filled vesicles capable of performing a rudimentary metabolism (and possibly self-reproduction), is still one of the big unsolved questions in origin of life. We have recently used lipid vesicles (liposomes) as primitive cell models, aiming at the study of the physical mechanisms for macromolecules encapsulation. We have reported that proteins and ribosomes can be encapsulated very efficiently, against statistical expectations, inside a small number of liposomes. Moreover the transcription-translation mixture, which realistically mimics a sort of minimal metabolic network, can be functionally reconstituted in liposomes owing to a self-concentration mechanism. Here we firstly summarize the recent advancements in this research line, highlighting how these results open a new vista on the phenomena that could have been important for the formation of functional primitive cells. Then, we present new evidences on the non-random entrapment of macromolecules (proteins, dextrans) in phospholipid vesicle, and in particular we show how enzymatic reactions can be accelerated because of the enhancement of their concentration inside liposomes.

No MeSH data available.


Related in: MedlinePlus

Experimental strategy for co-encapsulating an enzyme (proteinase K, black spots) and a macromolecular substrate (BSA-FITC, pink spots) inside lipid vesicles. Note that the external solutes have not been removed and can react outside vesicles.
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life-05-00969-f014: Experimental strategy for co-encapsulating an enzyme (proteinase K, black spots) and a macromolecular substrate (BSA-FITC, pink spots) inside lipid vesicles. Note that the external solutes have not been removed and can react outside vesicles.

Mentions: Next, we carried out the co-encapsulation experiment, consisting in preparing a mixture of proteinase K (1 μM) and BSA-FITC (2.5–5.0 μM), and forming liposomes in situ (Figure 14). The idea is that because both reactants are macromolecules, both can spontaneously concentrate inside liposomes during the membrane closure. For practical reasons (limit of detection), the concentration of BSA-FITC (the substrate) cannot be reduced too much, so that the actual experimental setup does not strictly correspond to the example illustrated in Figure 9 (self-concentration of the substrate from a value below to one above KM), but it just follows the same principles.


Physical Routes to Primitive Cells: An Experimental Model Based on the Spontaneous Entrapment of Enzymes inside Micrometer-Sized Liposomes.

D'Aguanno E, Altamura E, Mavelli F, Fahr A, Stano P, Luisi PL - Life (Basel) (2015)

Experimental strategy for co-encapsulating an enzyme (proteinase K, black spots) and a macromolecular substrate (BSA-FITC, pink spots) inside lipid vesicles. Note that the external solutes have not been removed and can react outside vesicles.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4390888&req=5

life-05-00969-f014: Experimental strategy for co-encapsulating an enzyme (proteinase K, black spots) and a macromolecular substrate (BSA-FITC, pink spots) inside lipid vesicles. Note that the external solutes have not been removed and can react outside vesicles.
Mentions: Next, we carried out the co-encapsulation experiment, consisting in preparing a mixture of proteinase K (1 μM) and BSA-FITC (2.5–5.0 μM), and forming liposomes in situ (Figure 14). The idea is that because both reactants are macromolecules, both can spontaneously concentrate inside liposomes during the membrane closure. For practical reasons (limit of detection), the concentration of BSA-FITC (the substrate) cannot be reduced too much, so that the actual experimental setup does not strictly correspond to the example illustrated in Figure 9 (self-concentration of the substrate from a value below to one above KM), but it just follows the same principles.

Bottom Line: We have reported that proteins and ribosomes can be encapsulated very efficiently, against statistical expectations, inside a small number of liposomes.Moreover the transcription-translation mixture, which realistically mimics a sort of minimal metabolic network, can be functionally reconstituted in liposomes owing to a self-concentration mechanism.Here we firstly summarize the recent advancements in this research line, highlighting how these results open a new vista on the phenomena that could have been important for the formation of functional primitive cells.

View Article: PubMed Central - PubMed

Affiliation: Science Department, Roma Tre University, Viale G. Marconi 446, I-00146 Rome, Italy. Alfred.Fahr@uni-jena.de.

ABSTRACT
How did primitive living cells originate? The formation of early cells, which were probably solute-filled vesicles capable of performing a rudimentary metabolism (and possibly self-reproduction), is still one of the big unsolved questions in origin of life. We have recently used lipid vesicles (liposomes) as primitive cell models, aiming at the study of the physical mechanisms for macromolecules encapsulation. We have reported that proteins and ribosomes can be encapsulated very efficiently, against statistical expectations, inside a small number of liposomes. Moreover the transcription-translation mixture, which realistically mimics a sort of minimal metabolic network, can be functionally reconstituted in liposomes owing to a self-concentration mechanism. Here we firstly summarize the recent advancements in this research line, highlighting how these results open a new vista on the phenomena that could have been important for the formation of functional primitive cells. Then, we present new evidences on the non-random entrapment of macromolecules (proteins, dextrans) in phospholipid vesicle, and in particular we show how enzymatic reactions can be accelerated because of the enhancement of their concentration inside liposomes.

No MeSH data available.


Related in: MedlinePlus