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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

(a) Experimental strategy for co-encapsulating an enzyme (carbonic anhydrase, CA, black spots) inside lipid vesicles, followed by adding a membrane-permeable substrate (6-carboxyfluorescein diacetate, CFDA). Note that the external enzyme molecules have not been removed and can react outside vesicles. (b) Details of the system under study, showing that CFDA can either react outside vesicles with free CA either permeate through the lipid membrane, reach the vesicle lumen, and then react with the encapsulated CA. The green-fluorescent product, 6-carboxyfluorescein, has been marked by a green box.
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life-05-00969-f010: (a) Experimental strategy for co-encapsulating an enzyme (carbonic anhydrase, CA, black spots) inside lipid vesicles, followed by adding a membrane-permeable substrate (6-carboxyfluorescein diacetate, CFDA). Note that the external enzyme molecules have not been removed and can react outside vesicles. (b) Details of the system under study, showing that CFDA can either react outside vesicles with free CA either permeate through the lipid membrane, reach the vesicle lumen, and then react with the encapsulated CA. The green-fluorescent product, 6-carboxyfluorescein, has been marked by a green box.

Mentions: The experimental plan is as it follows. Liposomes are formed in a solution containing CA, so that some of them will presumably contain an excess number of CA molecules due to spontaneous super-concentration of this macromolecule (29 kDa) in the liposome lumen. Next, CFDA is added and it will react both with free (external) and encapsulated CA, with the caveats that in the latter case CFDA shall first permeate the liposome membrane (Figure 10). Consequently, a comparison between the rates of bulk and liposomal reaction will reveal whether and what extent super-filled CA-containing liposomes form spontaneously.


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)

(a) Experimental strategy for co-encapsulating an enzyme (carbonic anhydrase, CA, black spots) inside lipid vesicles, followed by adding a membrane-permeable substrate (6-carboxyfluorescein diacetate, CFDA). Note that the external enzyme molecules have not been removed and can react outside vesicles. (b) Details of the system under study, showing that CFDA can either react outside vesicles with free CA either permeate through the lipid membrane, reach the vesicle lumen, and then react with the encapsulated CA. The green-fluorescent product, 6-carboxyfluorescein, has been marked by a green box.
© Copyright Policy
Related In: Results  -  Collection

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

life-05-00969-f010: (a) Experimental strategy for co-encapsulating an enzyme (carbonic anhydrase, CA, black spots) inside lipid vesicles, followed by adding a membrane-permeable substrate (6-carboxyfluorescein diacetate, CFDA). Note that the external enzyme molecules have not been removed and can react outside vesicles. (b) Details of the system under study, showing that CFDA can either react outside vesicles with free CA either permeate through the lipid membrane, reach the vesicle lumen, and then react with the encapsulated CA. The green-fluorescent product, 6-carboxyfluorescein, has been marked by a green box.
Mentions: The experimental plan is as it follows. Liposomes are formed in a solution containing CA, so that some of them will presumably contain an excess number of CA molecules due to spontaneous super-concentration of this macromolecule (29 kDa) in the liposome lumen. Next, CFDA is added and it will react both with free (external) and encapsulated CA, with the caveats that in the latter case CFDA shall first permeate the liposome membrane (Figure 10). Consequently, a comparison between the rates of bulk and liposomal reaction will reveal whether and what extent super-filled CA-containing liposomes form spontaneously.

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