Tuning the lipid bilayer: the influence of small molecules on domain formation and membrane fusion

Rianne Bartelds

Tuning the lipid bilayer: the influence of small molecules on domain formation and membrane fusion

Vertaalde titel van de bijdrage: De lipide bilagen beinvloeden: het effect van kleine moleculen op de vorming van domeinen en membraanfusie

Rianne Bartelds

Enzymologie

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Alle levende organismen bestaan uit cellen omgeven door een membraan. Dit membraan bestaat uit een lipide bilaag welke transport-, receptor- en kanaaleiwitten bevat. Verwacht wordt dat membranen domeinen bevatten, genaamd ‘rafts’. Eiwitten associeren met deze rafts of worden juist buitengesloten, waardoor bepaalde eiwitten dicht bij elkaar komen of juist bij elkaar uit de buurt worden gehouden.
Omdat rafts zo klein zijn en dynamisch, zijn modelsystemen ontwikkeld om interacties tussen lipiden en eiwitlocalisatie te kunnen onderzoeken. Één van deze model membranen zijn gigantische unilamellaire vesikels (GUVs), welke tientallen micrometers groot kunnen zijn en daardoor bestudeerd kunnen worden met lichtmicroscopie. GUVs bestaande uit drie verzadigde en onverzadigde lipiden en cholesterol scheiden in twee fasen: een dichte geordende vloeibare Lo fase en een meer vloeibare Ld fase.
In dit proefschrift heb ik laten zien dat kleine moleculen zoals suikers, koolwaterstoffen en bepaalde lipiden de fase scheiding beïnvloeden. De verdeling (partitie) van het model peptide WALP over de Lo en Ld domeinen van de membraan is bestudeerd.
Het tweede deel van dit proefschrift is gericht op kleinere vesikels, zogenoemde grote-unilamellaire vesikels (LUVs). Vesikels gemaakt van niet-ionogene oppervlakte-actieve stoffen zijn gekarakteriseerd. Ik laat zien dat deze vetachtige stoffen gesloten vesikels kunnen vormen, niosomen genoemd, die qua eigenschappen te vergelijken zijn met vesikels gebaseerd op lipiden.
Membraanfusie een delicate balans is tussen het verstoren van het membraan en handhaven van de permeabiliteitsbarriere. Ik ben er in geslaagd membraanfusie te realiseren zonder noemenswaardige lekkage van de vesikelinhoud door gebruik te maken van een enzym welke de kopgroepen van een deel van de lipiden afknipt.

Vertaalde titel van de bijdrage	De lipide bilagen beinvloeden: het effect van kleine moleculen op de vorming van domeinen en membraanfusie
Originele taal-2	English
Kwalificatie	Doctor of Philosophy
Toekennende instantie	Rijksuniversiteit Groningen
Begeleider(s)/adviseur	Poolman, Berend, Supervisor
Datum van toekenning	16-feb.-2018
Plaats van publicatie	[Groningen]
Uitgever	Rijksuniversiteit Groningen
Gedrukte ISBN's	978-94-034-0371-7
Elektronische ISBN's	978-94-034-0370-0
Status	Published - 2018

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Title and contentsFinal publisher's version, 74,2 KB
Chapter 1Final publisher's version, 1,44 MB
Chapter 2Final publisher's version, 2,96 MB
Chapter 3Final publisher's version, 935 KB
Chapter 4Final publisher's version, 2,5 MB
Chapter 5Final publisher's version, 2,7 MB
Chapter 6Final publisher's version, 2,65 MB
SummaryFinal publisher's version, 38,8 KB
Nederlandse samenvattingFinal publisher's version, 39,8 KB
DankwoordFinal publisher's version, 40,4 KB
Complete thesisFinal publisher's version, 13,5 MB
PropositionsFinal publisher's version, 108 KB

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title = "Tuning the lipid bilayer: the influence of small molecules on domain formation and membrane fusion",

abstract = "The eukaryotic cell membrane is a highly regulated, heterogeneous lipid bilayer that embeds transport, receptor and channel proteins as well as membrane-bound enzymes. The membrane is thought to have domains, named rafts. Proteins associate with rafts or are excluded, which brings proteins together or isolates them from others. Since these rafts are very small and short-lived, model membranes have been developed to study lipid-lipid interactions and protein partitioning. One of these model membrane systems are giant unilamellar vesicles (GUVs), micrometer-size vesicles that can be studied by light microscopy. Three component GUVs consisting of a saturated lipid, an unsaturated lipid and cholesterol can phase separate into a dense liquid-ordered (Lo) and more fluid liquid-disordered (Ld) phase.In this thesis, I have shown that small molecules such as some sugars, specific hydrocarbons and certain lipids influence the phase separation of this model membrane. The partitioning of the model peptide WALP in the Lo and Ld phase is described. The second part of this thesis focuses on small vesicles, so-called large-unilamellar vesicles (LUVs). Vesicles made from non-ionic surfactants, single-chain amphiphiles, were characterized. These molecules are shown to form closed, stable vesicles that may be a cost-effective alternative for already existing liposome-based drug formulations.Membrane fusion requires a delicate balance between disturbing the membrane, needed for fusion, and minimizing content leakage. I show that non-leaky fusion with relatively high yields can be obtained using a commercially available enzyme that cuts off a fraction of lipid head groups.",

author = "Rianne Bartelds",

year = "2018",

language = "English",

isbn = "978-94-034-0371-7",

publisher = "Rijksuniversiteit Groningen",

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TY - BOOK

T1 - Tuning the lipid bilayer: the influence of small molecules on domain formation and membrane fusion

AU - Bartelds, Rianne

PY - 2018

Y1 - 2018

N2 - The eukaryotic cell membrane is a highly regulated, heterogeneous lipid bilayer that embeds transport, receptor and channel proteins as well as membrane-bound enzymes. The membrane is thought to have domains, named rafts. Proteins associate with rafts or are excluded, which brings proteins together or isolates them from others. Since these rafts are very small and short-lived, model membranes have been developed to study lipid-lipid interactions and protein partitioning. One of these model membrane systems are giant unilamellar vesicles (GUVs), micrometer-size vesicles that can be studied by light microscopy. Three component GUVs consisting of a saturated lipid, an unsaturated lipid and cholesterol can phase separate into a dense liquid-ordered (Lo) and more fluid liquid-disordered (Ld) phase.In this thesis, I have shown that small molecules such as some sugars, specific hydrocarbons and certain lipids influence the phase separation of this model membrane. The partitioning of the model peptide WALP in the Lo and Ld phase is described. The second part of this thesis focuses on small vesicles, so-called large-unilamellar vesicles (LUVs). Vesicles made from non-ionic surfactants, single-chain amphiphiles, were characterized. These molecules are shown to form closed, stable vesicles that may be a cost-effective alternative for already existing liposome-based drug formulations.Membrane fusion requires a delicate balance between disturbing the membrane, needed for fusion, and minimizing content leakage. I show that non-leaky fusion with relatively high yields can be obtained using a commercially available enzyme that cuts off a fraction of lipid head groups.

AB - The eukaryotic cell membrane is a highly regulated, heterogeneous lipid bilayer that embeds transport, receptor and channel proteins as well as membrane-bound enzymes. The membrane is thought to have domains, named rafts. Proteins associate with rafts or are excluded, which brings proteins together or isolates them from others. Since these rafts are very small and short-lived, model membranes have been developed to study lipid-lipid interactions and protein partitioning. One of these model membrane systems are giant unilamellar vesicles (GUVs), micrometer-size vesicles that can be studied by light microscopy. Three component GUVs consisting of a saturated lipid, an unsaturated lipid and cholesterol can phase separate into a dense liquid-ordered (Lo) and more fluid liquid-disordered (Ld) phase.In this thesis, I have shown that small molecules such as some sugars, specific hydrocarbons and certain lipids influence the phase separation of this model membrane. The partitioning of the model peptide WALP in the Lo and Ld phase is described. The second part of this thesis focuses on small vesicles, so-called large-unilamellar vesicles (LUVs). Vesicles made from non-ionic surfactants, single-chain amphiphiles, were characterized. These molecules are shown to form closed, stable vesicles that may be a cost-effective alternative for already existing liposome-based drug formulations.Membrane fusion requires a delicate balance between disturbing the membrane, needed for fusion, and minimizing content leakage. I show that non-leaky fusion with relatively high yields can be obtained using a commercially available enzyme that cuts off a fraction of lipid head groups.

M3 - Thesis fully internal (DIV)

SN - 978-94-034-0371-7

PB - Rijksuniversiteit Groningen

CY - [Groningen]

ER -

Tuning the lipid bilayer: the influence of small molecules on domain formation and membrane fusion

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