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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

Examples of mini-enzymatic pathways (2, 3, and 4 steps, respectively) that could be constructed inside lipid vesicles. Abbreviations: GO: glucose oxidase; HRP: horseradish peroxidase; GLN: glutaminase; GLDH: glutamate dehydrogenase; DIA: diaphorase; INV: invertase; HK: hexokinase; G6PDH: glucose-6-phosphate dehydrogenase.
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life-05-00969-f015: Examples of mini-enzymatic pathways (2, 3, and 4 steps, respectively) that could be constructed inside lipid vesicles. Abbreviations: GO: glucose oxidase; HRP: horseradish peroxidase; GLN: glutaminase; GLDH: glutamate dehydrogenase; DIA: diaphorase; INV: invertase; HK: hexokinase; G6PDH: glucose-6-phosphate dehydrogenase.

Mentions: The strategy is based on the production of a fluorescent molecule downstream of a multi-step enzymatic pathway. In this respect, two enzymes are particularly useful, i.e., peroxidase and diaphorase (i.e., a NAD(P)H dehydrogenase). Peroxidase uses hydrogen peroxide for oxidizing fluorogenic substrates such as reduced fluorescein (fluorescin), reduced rhodamine, or the so-called Amplex Red© (a phenoxazine derivative) to give, respectively, fluorescein, rhodamine, and resorufin. Diaphorase uses NAD(P)H for reducing resazurin to resorufin. The activity of these two enzymes can be combined with other reactions in order to build fluorescence-detectable enzyme-catalyzed mini-pathways to be reconstructed inside vesicles. Figure 15 shows just some examples of such possible systems.


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)

Examples of mini-enzymatic pathways (2, 3, and 4 steps, respectively) that could be constructed inside lipid vesicles. Abbreviations: GO: glucose oxidase; HRP: horseradish peroxidase; GLN: glutaminase; GLDH: glutamate dehydrogenase; DIA: diaphorase; INV: invertase; HK: hexokinase; G6PDH: glucose-6-phosphate dehydrogenase.
© Copyright Policy
Related In: Results  -  Collection

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

life-05-00969-f015: Examples of mini-enzymatic pathways (2, 3, and 4 steps, respectively) that could be constructed inside lipid vesicles. Abbreviations: GO: glucose oxidase; HRP: horseradish peroxidase; GLN: glutaminase; GLDH: glutamate dehydrogenase; DIA: diaphorase; INV: invertase; HK: hexokinase; G6PDH: glucose-6-phosphate dehydrogenase.
Mentions: The strategy is based on the production of a fluorescent molecule downstream of a multi-step enzymatic pathway. In this respect, two enzymes are particularly useful, i.e., peroxidase and diaphorase (i.e., a NAD(P)H dehydrogenase). Peroxidase uses hydrogen peroxide for oxidizing fluorogenic substrates such as reduced fluorescein (fluorescin), reduced rhodamine, or the so-called Amplex Red© (a phenoxazine derivative) to give, respectively, fluorescein, rhodamine, and resorufin. Diaphorase uses NAD(P)H for reducing resazurin to resorufin. The activity of these two enzymes can be combined with other reactions in order to build fluorescence-detectable enzyme-catalyzed mini-pathways to be reconstructed inside vesicles. Figure 15 shows just some examples of such possible systems.

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