Michele Fiore - Academia.edu (original) (raw)

Papers by Michele Fiore

Life

Aristotle considered that “nature does not do anything endless” [...]

iScience, 2020

The reproduction of the shape of giant vesicles usually results in the increase of their ''popula... more The reproduction of the shape of giant vesicles usually results in the increase of their ''population'' size. This may be achieved on giant vesicles by appropriately supplying ''mother'' vesicles with membranogenic amphiphiles. The next ''generation'' of ''daughter'' vesicles obtained from this ''feeding'' is inherently difficult to distinguish from the original mothers. Here we report on a method for the consecutive feeding with different fatty acids that each provoke membrane growth and detachment of daughter vesicles from glass microsphere-supported phospholipidic mother vesicles. We discovered that a saturated fatty acid was carried over to the next generation of mothers better than two unsaturated congeners. This has an important bearing on the growth and replication of primitive compartments at the early stages of life. Microsphere-supported vesicles are also a precise analytical tool.

Beilstein Journal of Organic Chemistry, 2019

A series of alkyl thioglycosides and alkyl thiodiglycosides bearing glucose and N-acetylglucosami... more A series of alkyl thioglycosides and alkyl thiodiglycosides bearing glucose and N-acetylglucosamine residues were prepared by thiol–ene coupling in moderate to good yields (40–85%). Their binding ability towards wheat germ agglutinin was measured by competitive enzyme-linked lectin assays. One of the synthetic compounds presenting two GlcNAc units showed the highest inhibitory effect of this study with an IC50 of 11 µM corresponding to a 3182-fold improvement compared to GlcNAc. These synthetic molecules were used to produce giant vesicles, alone or in mixture with phospholipids, mimicking bacterial outer membrane vesicles (OMV) with potential antiadhesive properties.

Organic & Biomolecular Chemistry, 2017

Correction for ‘Giant vesicles from rehydrated crude mixtures containing unexpected mixtures of a... more Correction for ‘Giant vesicles from rehydrated crude mixtures containing unexpected mixtures of amphiphiles formed under plausibly prebiotic conditions’ by Michele Fiore et al., Org. Biomol. Chem., 2017, 15, 4231–4240.

Organic & Biomolecular Chemistry, 2017

Giant lipid vesicles resemble compartments of biological cells, mimicking them in their dimension... more Giant lipid vesicles resemble compartments of biological cells, mimicking them in their dimension, membrane structure and partly in their membrane composition.

Life (Basel, Switzerland), Jan 28, 2016

It is still uncertain how the first minimal cellular systems evolved to the complexity required f... more It is still uncertain how the first minimal cellular systems evolved to the complexity required for life to begin, but it is obvious that the role of amphiphilic compounds in the origin of life is one of huge relevance. Over the last four decades a number of studies have demonstrated how amphiphilic molecules can be synthesized under plausibly prebiotic conditions. The majority of these experiments also gave evidence for the ability of so formed amphiphiles to assemble in closed membranes of vesicles that, in principle, could have compartmented first biological processes on early Earth, including the emergence of self-replicating systems. For a competitive selection of the best performing molecular replicators to become operative, some kind of bounded units capable of harboring them are indispensable. Without the competition between dynamic populations of different compartments, life itself could not be distinguished from an otherwise disparate array or network of molecular interact...

Organic & Biomolecular Chemistry, 2015

We report a synthetic strategy to prepare hexadecavalent glycodendrimers that can be used in both... more We report a synthetic strategy to prepare hexadecavalent glycodendrimers that can be used in both divergent and convergent route with similar efficiency.

Symmetry

In the prebiotic world, the chemical assembly of biotic building blocks led to racemic mixtures; ... more In the prebiotic world, the chemical assembly of biotic building blocks led to racemic mixtures; however, homo-chirality emerged in the racemic prebiotic soup. Polymers and other molecules assembled from mixtures of enantiomers rather than racemic ones. Understanding how symmetry breaking happens is one of the most challenging fields of research in origin of life studies. With this article, we aim to shed light on one of the problems: in the absence of physical examples for use in a laboratory scale, what are the best models to use to simulate the conditions and lead to homo-chiral symmetry breaking? In this perspective, we suggest looking to chemical models that can represent a poorly studied class of prebiotic compounds in the context of symmetry breaking: the phospholipids.

Angewandte Chemie International Edition, 2016

Diplodia corticola , anamorph of Botryosphaeria corticola Phillips, Alves et Luque, and Biscognau... more Diplodia corticola , anamorph of Botryosphaeria corticola Phillips, Alves et Luque, and Biscognauxia mediterranea (De Not.) O. Kuntze (= Hypoxylon mediterraneum) have often been associated with serious decline phenomena, which have been affecting the cork oak forest in Italy and other Mediterranean countries for several years. Diplodia corticola is widespread in Sardinian oak forests, and can affect plants of different ages, inducing symptoms which include dieback, cankers and vascular necrosis. These studies may provide information which could be useful for understanding the chemistry and the biology governing the relationship between these fungi and their hosts. Further studies should aim to also evaluate the ecological role of these substances.

Goldschmidt2021 abstracts

International Journal of Molecular Sciences

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Proceedings of the National Academy of Sciences

The construction of energetically autonomous artificial protocells is one of the most ambitious g... more The construction of energetically autonomous artificial protocells is one of the most ambitious goals in bottom-up synthetic biology. Here, we show an efficient manner to build adenosine 5′-triphosphate (ATP) synthesizing hybrid multicompartment protocells. Bacterial chromatophores from Rhodobacter sphaeroides accomplish the photophosphorylation of adenosine 5′-diphosphate (ADP) to ATP, functioning as nanosized photosynthetic organellae when encapsulated inside artificial giant phospholipid vesicles (ATP production rate up to ∼100 ATP∙s−1 per ATP synthase). The chromatophore morphology and the orientation of the photophosphorylation proteins were characterized by cryo-electron microscopy (cryo-EM) and time-resolved spectroscopy. The freshly synthesized ATP has been employed for sustaining the transcription of a DNA gene, following the RNA biosynthesis inside individual vesicles by confocal microscopy. The hybrid multicompartment approach here proposed is very promising for the const...

Symmetry

Although prebiotic condensations of glycerol, phosphate and fatty acids produce phospholipid este... more Although prebiotic condensations of glycerol, phosphate and fatty acids produce phospholipid esters with a racemic backbone, most experimental studies on vesicles intended as protocell models have been carried out by employing commercial enantiopure phospholipids. Current experimental research on realistic protocell models urgently requires racemic phospholipids and efficient synthetic routes for their production. Here we propose three synthetic pathways starting from glycerol or from racemic solketal (α,β-isopropylidene-dl-glycerol) for the gram-scale production (up to 4 g) of racemic phospholipid ester precursors. We describe and compare these synthetic pathways with literature data. Racemic phosphatidylcholines and phosphatidylethanolamines were obtained in good yields and high purity from 1,2-diacylglycerols. Racemic POPC (rac-POPC, (R,S)-1-palmitoyl-2-oleoyl-3-phosphocholine), was used as a model compound for the preparation of giant vesicles (GVs). Confocal laser scanning fluo...

Symmetry

Either stereo reactants or stereo catalysis from achiral or chiral molecules are a prerequisite t... more Either stereo reactants or stereo catalysis from achiral or chiral molecules are a prerequisite to obtain pure enantiomeric lipid derivatives. We reviewed a few plausibly organic syntheses of phospholipids under prebiotic conditions with special attention paid to the starting materials as pro-chiral dihydroxyacetone and dihydroxyacetone phosphate (DHAP), which are the key molecules to break symmetry in phospholipids. The advantages of homochiral membranes compared to those of heterochiral membranes were analysed in terms of specific recognition, optimal functions of enzymes, membrane fluidity and topological packing. All biological membranes contain enantiomerically pure lipids in modern bacteria, eukarya and archaea. The contemporary archaea, comprising of methanogens, halobacteria and thermoacidophiles, are living under extreme conditions reminiscent of primitive environment and may indicate the origin of one ancient evolution path of lipid biosynthesis. The analysis of the known ...

PLOS ONE

Giant lipid vesicles (GVs) are emerging models for investigating the properties and reactivity of... more Giant lipid vesicles (GVs) are emerging models for investigating the properties and reactivity of cell-like microcompartments, providing useful information about plausible protocellular structures in primitive times, as well as for the modern synthetic biology goal of constructing the first artificial cell from its reconstituted and partly modified components. Here we explore a novel methodology of GV purification by microfiltration under reduced pressure, operated by a simple apparatus. The method has been characterized in terms of flow rate, amount of lipid loss, quality of recovered GVs, and size distribution. A case study is reported to show the practicability of GV microfiltration. A clickable fluorescent probe was encapsulated inside GVs; more than 99.9% of the non-entrapped probe was easily and rapidly removed by multiple microfiltrations. This novel methodology is briefly discussed as a future tool for selection experiments on GV populations.

Organic & Biomolecular Chemistry

Nucleic acids, phospholipids and other organic phosphates play central roles in biological pathways.

Bioconjugate chemistry, Jan 17, 2018

Bacterial and fungal pathogens involved in lung infection in cystic fibrosis patients utilize a p... more Bacterial and fungal pathogens involved in lung infection in cystic fibrosis patients utilize a particular family of glycan-binding proteins, characterized by the presentation of six fucose-binding sites on a ring-shaped scaffold. These lectins are attractive targets for anti-infectious compounds that could interfere in the recognition of host tissues by pathogens. The design of a cyclopeptide-based hexavalent structure allowed for the presentation of six fucose residues. The synthetic hexavalent compound displays liable geometry resulting in high-avidity binding by lectins from Aspergillus fumigatus and Burkholderia ambifaria. Replacing the fucose residue with a conformationally constrained fucomimetic does not alter the affinity and provides fine specificity with no binding to other fucose-specific lectins.

Scientific reports, Jan 22, 2017

It is an open question how the chemical structure of prebiotic vesicle-forming amphiphiles comple... more It is an open question how the chemical structure of prebiotic vesicle-forming amphiphiles complexified to produce robust primitive compartments that could safely host foreign molecules. Previous work suggests that comparingly labile vesicles composed of plausibly prebiotic fatty acids were eventually chemically transformed with glycerol and a suitable phosphate source into phospholipids that would form robust vesicles. Here we show that phosphatidic acid (PA) and phosphatidylethanolamine (PE) lipids can be obtained from racemic dioleoyl glycerol under plausibly prebiotic phosphorylation conditions. Upon in situ hydration of the crude phosphorylation mixtures only those that contained rac-DOPA (not rac-DOPE) generated stable giant vesicles that were capable of encapsulating water-soluble probes, as evidenced by confocal microscopy and flow cytometry. Chemical reaction side-products (identified by IR and MS and quantified by 1H NMR) acted as co-surfactants and facilitated vesicle for...

Angewandte Chemie (International ed. in English), Jan 6, 2017

Growth and division experiments on phospholipid boundaries were carried out using glass microsphe... more Growth and division experiments on phospholipid boundaries were carried out using glass microsphere-supported phospholipid (DOPC) giant vesicles (GVs) fed with a fatty acid solution (oleic acid) at two distinct feeding rates. Both fast and slow feeding methods produced daughter GVs. Under slow feeding conditions the membrane growth process (evagination, buds, filaments) was observed in detail by fluorescence microscopy. The density difference between supported mother vesicles and newly formed daughter vesicles allowed their easy separation. Mass spectrometric analysis of the resulting mother and daughter GVs showed that the composition of both vesicle types was a mixture of original supported phospholipids and added fatty acids reflecting the total composition of amphiphiles after the feeding process. Thus, self-reproduction of phospholipid vesicles can take place under preservation of the lipid composition but different aggregate size.

Life

Aristotle considered that “nature does not do anything endless” [...]

iScience, 2020

The reproduction of the shape of giant vesicles usually results in the increase of their ''popula... more The reproduction of the shape of giant vesicles usually results in the increase of their ''population'' size. This may be achieved on giant vesicles by appropriately supplying ''mother'' vesicles with membranogenic amphiphiles. The next ''generation'' of ''daughter'' vesicles obtained from this ''feeding'' is inherently difficult to distinguish from the original mothers. Here we report on a method for the consecutive feeding with different fatty acids that each provoke membrane growth and detachment of daughter vesicles from glass microsphere-supported phospholipidic mother vesicles. We discovered that a saturated fatty acid was carried over to the next generation of mothers better than two unsaturated congeners. This has an important bearing on the growth and replication of primitive compartments at the early stages of life. Microsphere-supported vesicles are also a precise analytical tool.

Beilstein Journal of Organic Chemistry, 2019

A series of alkyl thioglycosides and alkyl thiodiglycosides bearing glucose and N-acetylglucosami... more A series of alkyl thioglycosides and alkyl thiodiglycosides bearing glucose and N-acetylglucosamine residues were prepared by thiol–ene coupling in moderate to good yields (40–85%). Their binding ability towards wheat germ agglutinin was measured by competitive enzyme-linked lectin assays. One of the synthetic compounds presenting two GlcNAc units showed the highest inhibitory effect of this study with an IC50 of 11 µM corresponding to a 3182-fold improvement compared to GlcNAc. These synthetic molecules were used to produce giant vesicles, alone or in mixture with phospholipids, mimicking bacterial outer membrane vesicles (OMV) with potential antiadhesive properties.

Organic & Biomolecular Chemistry, 2017

Correction for ‘Giant vesicles from rehydrated crude mixtures containing unexpected mixtures of a... more Correction for ‘Giant vesicles from rehydrated crude mixtures containing unexpected mixtures of amphiphiles formed under plausibly prebiotic conditions’ by Michele Fiore et al., Org. Biomol. Chem., 2017, 15, 4231–4240.

Organic & Biomolecular Chemistry, 2017

Giant lipid vesicles resemble compartments of biological cells, mimicking them in their dimension... more Giant lipid vesicles resemble compartments of biological cells, mimicking them in their dimension, membrane structure and partly in their membrane composition.

Life (Basel, Switzerland), Jan 28, 2016

It is still uncertain how the first minimal cellular systems evolved to the complexity required f... more It is still uncertain how the first minimal cellular systems evolved to the complexity required for life to begin, but it is obvious that the role of amphiphilic compounds in the origin of life is one of huge relevance. Over the last four decades a number of studies have demonstrated how amphiphilic molecules can be synthesized under plausibly prebiotic conditions. The majority of these experiments also gave evidence for the ability of so formed amphiphiles to assemble in closed membranes of vesicles that, in principle, could have compartmented first biological processes on early Earth, including the emergence of self-replicating systems. For a competitive selection of the best performing molecular replicators to become operative, some kind of bounded units capable of harboring them are indispensable. Without the competition between dynamic populations of different compartments, life itself could not be distinguished from an otherwise disparate array or network of molecular interact...

Organic & Biomolecular Chemistry, 2015

We report a synthetic strategy to prepare hexadecavalent glycodendrimers that can be used in both... more We report a synthetic strategy to prepare hexadecavalent glycodendrimers that can be used in both divergent and convergent route with similar efficiency.

Symmetry

In the prebiotic world, the chemical assembly of biotic building blocks led to racemic mixtures; ... more In the prebiotic world, the chemical assembly of biotic building blocks led to racemic mixtures; however, homo-chirality emerged in the racemic prebiotic soup. Polymers and other molecules assembled from mixtures of enantiomers rather than racemic ones. Understanding how symmetry breaking happens is one of the most challenging fields of research in origin of life studies. With this article, we aim to shed light on one of the problems: in the absence of physical examples for use in a laboratory scale, what are the best models to use to simulate the conditions and lead to homo-chiral symmetry breaking? In this perspective, we suggest looking to chemical models that can represent a poorly studied class of prebiotic compounds in the context of symmetry breaking: the phospholipids.

Angewandte Chemie International Edition, 2016

Diplodia corticola , anamorph of Botryosphaeria corticola Phillips, Alves et Luque, and Biscognau... more Diplodia corticola , anamorph of Botryosphaeria corticola Phillips, Alves et Luque, and Biscognauxia mediterranea (De Not.) O. Kuntze (= Hypoxylon mediterraneum) have often been associated with serious decline phenomena, which have been affecting the cork oak forest in Italy and other Mediterranean countries for several years. Diplodia corticola is widespread in Sardinian oak forests, and can affect plants of different ages, inducing symptoms which include dieback, cankers and vascular necrosis. These studies may provide information which could be useful for understanding the chemistry and the biology governing the relationship between these fungi and their hosts. Further studies should aim to also evaluate the ecological role of these substances.

Goldschmidt2021 abstracts

International Journal of Molecular Sciences

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Proceedings of the National Academy of Sciences

The construction of energetically autonomous artificial protocells is one of the most ambitious g... more The construction of energetically autonomous artificial protocells is one of the most ambitious goals in bottom-up synthetic biology. Here, we show an efficient manner to build adenosine 5′-triphosphate (ATP) synthesizing hybrid multicompartment protocells. Bacterial chromatophores from Rhodobacter sphaeroides accomplish the photophosphorylation of adenosine 5′-diphosphate (ADP) to ATP, functioning as nanosized photosynthetic organellae when encapsulated inside artificial giant phospholipid vesicles (ATP production rate up to ∼100 ATP∙s−1 per ATP synthase). The chromatophore morphology and the orientation of the photophosphorylation proteins were characterized by cryo-electron microscopy (cryo-EM) and time-resolved spectroscopy. The freshly synthesized ATP has been employed for sustaining the transcription of a DNA gene, following the RNA biosynthesis inside individual vesicles by confocal microscopy. The hybrid multicompartment approach here proposed is very promising for the const...

Symmetry

Although prebiotic condensations of glycerol, phosphate and fatty acids produce phospholipid este... more Although prebiotic condensations of glycerol, phosphate and fatty acids produce phospholipid esters with a racemic backbone, most experimental studies on vesicles intended as protocell models have been carried out by employing commercial enantiopure phospholipids. Current experimental research on realistic protocell models urgently requires racemic phospholipids and efficient synthetic routes for their production. Here we propose three synthetic pathways starting from glycerol or from racemic solketal (α,β-isopropylidene-dl-glycerol) for the gram-scale production (up to 4 g) of racemic phospholipid ester precursors. We describe and compare these synthetic pathways with literature data. Racemic phosphatidylcholines and phosphatidylethanolamines were obtained in good yields and high purity from 1,2-diacylglycerols. Racemic POPC (rac-POPC, (R,S)-1-palmitoyl-2-oleoyl-3-phosphocholine), was used as a model compound for the preparation of giant vesicles (GVs). Confocal laser scanning fluo...

Symmetry

Either stereo reactants or stereo catalysis from achiral or chiral molecules are a prerequisite t... more Either stereo reactants or stereo catalysis from achiral or chiral molecules are a prerequisite to obtain pure enantiomeric lipid derivatives. We reviewed a few plausibly organic syntheses of phospholipids under prebiotic conditions with special attention paid to the starting materials as pro-chiral dihydroxyacetone and dihydroxyacetone phosphate (DHAP), which are the key molecules to break symmetry in phospholipids. The advantages of homochiral membranes compared to those of heterochiral membranes were analysed in terms of specific recognition, optimal functions of enzymes, membrane fluidity and topological packing. All biological membranes contain enantiomerically pure lipids in modern bacteria, eukarya and archaea. The contemporary archaea, comprising of methanogens, halobacteria and thermoacidophiles, are living under extreme conditions reminiscent of primitive environment and may indicate the origin of one ancient evolution path of lipid biosynthesis. The analysis of the known ...

PLOS ONE

Giant lipid vesicles (GVs) are emerging models for investigating the properties and reactivity of... more Giant lipid vesicles (GVs) are emerging models for investigating the properties and reactivity of cell-like microcompartments, providing useful information about plausible protocellular structures in primitive times, as well as for the modern synthetic biology goal of constructing the first artificial cell from its reconstituted and partly modified components. Here we explore a novel methodology of GV purification by microfiltration under reduced pressure, operated by a simple apparatus. The method has been characterized in terms of flow rate, amount of lipid loss, quality of recovered GVs, and size distribution. A case study is reported to show the practicability of GV microfiltration. A clickable fluorescent probe was encapsulated inside GVs; more than 99.9% of the non-entrapped probe was easily and rapidly removed by multiple microfiltrations. This novel methodology is briefly discussed as a future tool for selection experiments on GV populations.

Organic & Biomolecular Chemistry

Nucleic acids, phospholipids and other organic phosphates play central roles in biological pathways.

Bioconjugate chemistry, Jan 17, 2018

Bacterial and fungal pathogens involved in lung infection in cystic fibrosis patients utilize a p... more Bacterial and fungal pathogens involved in lung infection in cystic fibrosis patients utilize a particular family of glycan-binding proteins, characterized by the presentation of six fucose-binding sites on a ring-shaped scaffold. These lectins are attractive targets for anti-infectious compounds that could interfere in the recognition of host tissues by pathogens. The design of a cyclopeptide-based hexavalent structure allowed for the presentation of six fucose residues. The synthetic hexavalent compound displays liable geometry resulting in high-avidity binding by lectins from Aspergillus fumigatus and Burkholderia ambifaria. Replacing the fucose residue with a conformationally constrained fucomimetic does not alter the affinity and provides fine specificity with no binding to other fucose-specific lectins.

Scientific reports, Jan 22, 2017

It is an open question how the chemical structure of prebiotic vesicle-forming amphiphiles comple... more It is an open question how the chemical structure of prebiotic vesicle-forming amphiphiles complexified to produce robust primitive compartments that could safely host foreign molecules. Previous work suggests that comparingly labile vesicles composed of plausibly prebiotic fatty acids were eventually chemically transformed with glycerol and a suitable phosphate source into phospholipids that would form robust vesicles. Here we show that phosphatidic acid (PA) and phosphatidylethanolamine (PE) lipids can be obtained from racemic dioleoyl glycerol under plausibly prebiotic phosphorylation conditions. Upon in situ hydration of the crude phosphorylation mixtures only those that contained rac-DOPA (not rac-DOPE) generated stable giant vesicles that were capable of encapsulating water-soluble probes, as evidenced by confocal microscopy and flow cytometry. Chemical reaction side-products (identified by IR and MS and quantified by 1H NMR) acted as co-surfactants and facilitated vesicle for...

Angewandte Chemie (International ed. in English), Jan 6, 2017

Growth and division experiments on phospholipid boundaries were carried out using glass microsphe... more Growth and division experiments on phospholipid boundaries were carried out using glass microsphere-supported phospholipid (DOPC) giant vesicles (GVs) fed with a fatty acid solution (oleic acid) at two distinct feeding rates. Both fast and slow feeding methods produced daughter GVs. Under slow feeding conditions the membrane growth process (evagination, buds, filaments) was observed in detail by fluorescence microscopy. The density difference between supported mother vesicles and newly formed daughter vesicles allowed their easy separation. Mass spectrometric analysis of the resulting mother and daughter GVs showed that the composition of both vesicle types was a mixture of original supported phospholipids and added fatty acids reflecting the total composition of amphiphiles after the feeding process. Thus, self-reproduction of phospholipid vesicles can take place under preservation of the lipid composition but different aggregate size.