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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

Two alternative (and perhaps competitive) hypothetical mechanisms for the formation of the first protocells, whereby the first proteins (and enzymes) were constructed inside a compartment (bottom), or first outside, then incorporated inside (top). Redrawn, with minor modifications, from [13].
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life-05-00969-f002: Two alternative (and perhaps competitive) hypothetical mechanisms for the formation of the first protocells, whereby the first proteins (and enzymes) were constructed inside a compartment (bottom), or first outside, then incorporated inside (top). Redrawn, with minor modifications, from [13].

Mentions: How did primitive minimal cells originate? Even if these structures have, by definition, a minimal genetic/metabolic complexity, it is evident that they must contain hundreds of components, just to count the macromolecular (function-bearing) ones. Here two possibilities can be discussed (Figure 2). The first one is that the biochemical network developed firstly in the environment, and later become encapsulated inside lipid vesicles; the second one is that the network was born already within compartments, starting from simpler molecules. Both appear difficult. The first one because it is hundreds of macromolecules and small molecules should be encapsulated within the same lipid vesicle in order to have a functional cell; the second because during the (very long) process of network development, building blocks should enter the compartment, byproducts should leave it, and permeability should be somehow controlled in order to have such a sophisticated “bioreactor” that function correctly. Can experiments on semi-synthetic minimal cells—those that can be constructed in the laboratory—help to clarify, at least partially, such question?


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)

Two alternative (and perhaps competitive) hypothetical mechanisms for the formation of the first protocells, whereby the first proteins (and enzymes) were constructed inside a compartment (bottom), or first outside, then incorporated inside (top). Redrawn, with minor modifications, from [13].
© Copyright Policy
Related In: Results  -  Collection

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

life-05-00969-f002: Two alternative (and perhaps competitive) hypothetical mechanisms for the formation of the first protocells, whereby the first proteins (and enzymes) were constructed inside a compartment (bottom), or first outside, then incorporated inside (top). Redrawn, with minor modifications, from [13].
Mentions: How did primitive minimal cells originate? Even if these structures have, by definition, a minimal genetic/metabolic complexity, it is evident that they must contain hundreds of components, just to count the macromolecular (function-bearing) ones. Here two possibilities can be discussed (Figure 2). The first one is that the biochemical network developed firstly in the environment, and later become encapsulated inside lipid vesicles; the second one is that the network was born already within compartments, starting from simpler molecules. Both appear difficult. The first one because it is hundreds of macromolecules and small molecules should be encapsulated within the same lipid vesicle in order to have a functional cell; the second because during the (very long) process of network development, building blocks should enter the compartment, byproducts should leave it, and permeability should be somehow controlled in order to have such a sophisticated “bioreactor” that function correctly. Can experiments on semi-synthetic minimal cells—those that can be constructed in the laboratory—help to clarify, at least partially, such question?

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