Molecular interactions of hydrophobin proteins with their surroundings

Dissertation

Mathias S. Grunér

Research output: ThesisDissertationMonograph

Abstract

This thesis describes the properties of a group of proteins named hydro-phobins, which fulfil a variety of functions in the growth and function of filamentous fungi. Hydrophobins can be utilized as coatings/protective agents, in adhesion, in surface modifications and overall functions that require surfactant-like properties. This work is concentrated on the hydrophobins HFBI, HFBII and HFBIII expressed by Trichoderma reesei. The aims of this study were to examine in what manner hydrophobins function when interacting with their surroundings and how their surroundings affect their function. Hydrophobins were shown strongly to adhere to surfaces of varying polarity and structure by self-assembly, governed by their amphiphilic nature, and to adsorb with different orientation on hydrophilic and hydrophobic surfaces. The proteins were shown to selectively recruit other proteins and molecules to a self-assembled amphiphilic film of hydrophobin. HFBI variants bound to a surface were shown to recruit T. reesei enzymes specifically depending on localized protein surface charge on the hydrophilic part of the protein, and HFBII adsorbed on nanoparticles was shown to bind layers of human plasma proteins in different manner when adsorbed on nanoparticles of varying polarity. Surface films formed by hydrophobins were shown to be highly elastic, and charged residues on the side of the proteins were shown to have a role in stabilizing the protein films formed. The surroundings in which the proteins exist were shown to also affect their function. Surfaces of varying polarity in the protein surroundings affected how they self-assemble, and hydrophobin multimer exchange in solution was shown to be governed by hydrophobic interactions and the multimer exchange behaviour was shown to be affected by other proteins and molecules. HFBII and HFBI were shown to interact in solution, altering multimer kinetics and thermodynamics considerably. Solution association methods, surface characterization analysis methods and size measurement techniques such as stopped-flow spectroscopy, quartz crystal microbalance with dissipation and differential centrifugal sedimentation were used. The results presented here show that hydrophobins function by selectively interacting with their surroundings assembled at various interfaces specifically recruiting other proteins and molecules and that the surroundings in which the proteins exist also affects their function in terms of multimer exchange behaviour and surface adhesion properties. The knowledge learned here regarding hydrophobins, show that these proteins can be specialized to function as highly selective self-assembling building blocks in applications such as biosensors and biocompatible coatings, and gives new insight in the growth and function of filamentous fungi.
Original languageEnglish
QualificationDoctor Degree
Awarding Institution
  • Aalto University
Supervisors/Advisors
  • Linder, Markus, Supervisor, External person
Award date10 Dec 2015
Publisher
Print ISBNs978-951-38-8367-6
Electronic ISBNs978-951-38-8366-9
Publication statusPublished - 2015
MoE publication typeG4 Doctoral dissertation (monograph)

Fingerprint

Molecular interactions
Proteins
Fungi
Molecules
Adhesion
Nanoparticles
Protective Agents
Coatings
Quartz crystal microbalances
Surface charge
Sedimentation
Biosensors
Surface-Active Agents
Self assembly
Surface treatment
Blood Proteins
Ion exchange
Association reactions
Spectroscopy
Thermodynamics

Keywords

  • hydrophobin
  • self-assembly
  • HFBI
  • HFBII
  • adhesion

Cite this

@phdthesis{272f36e395bb481ba3258c7e3a2aef30,
title = "Molecular interactions of hydrophobin proteins with their surroundings: Dissertation",
abstract = "This thesis describes the properties of a group of proteins named hydro-phobins, which fulfil a variety of functions in the growth and function of filamentous fungi. Hydrophobins can be utilized as coatings/protective agents, in adhesion, in surface modifications and overall functions that require surfactant-like properties. This work is concentrated on the hydrophobins HFBI, HFBII and HFBIII expressed by Trichoderma reesei. The aims of this study were to examine in what manner hydrophobins function when interacting with their surroundings and how their surroundings affect their function. Hydrophobins were shown strongly to adhere to surfaces of varying polarity and structure by self-assembly, governed by their amphiphilic nature, and to adsorb with different orientation on hydrophilic and hydrophobic surfaces. The proteins were shown to selectively recruit other proteins and molecules to a self-assembled amphiphilic film of hydrophobin. HFBI variants bound to a surface were shown to recruit T. reesei enzymes specifically depending on localized protein surface charge on the hydrophilic part of the protein, and HFBII adsorbed on nanoparticles was shown to bind layers of human plasma proteins in different manner when adsorbed on nanoparticles of varying polarity. Surface films formed by hydrophobins were shown to be highly elastic, and charged residues on the side of the proteins were shown to have a role in stabilizing the protein films formed. The surroundings in which the proteins exist were shown to also affect their function. Surfaces of varying polarity in the protein surroundings affected how they self-assemble, and hydrophobin multimer exchange in solution was shown to be governed by hydrophobic interactions and the multimer exchange behaviour was shown to be affected by other proteins and molecules. HFBII and HFBI were shown to interact in solution, altering multimer kinetics and thermodynamics considerably. Solution association methods, surface characterization analysis methods and size measurement techniques such as stopped-flow spectroscopy, quartz crystal microbalance with dissipation and differential centrifugal sedimentation were used. The results presented here show that hydrophobins function by selectively interacting with their surroundings assembled at various interfaces specifically recruiting other proteins and molecules and that the surroundings in which the proteins exist also affects their function in terms of multimer exchange behaviour and surface adhesion properties. The knowledge learned here regarding hydrophobins, show that these proteins can be specialized to function as highly selective self-assembling building blocks in applications such as biosensors and biocompatible coatings, and gives new insight in the growth and function of filamentous fungi.",
keywords = "hydrophobin, self-assembly, HFBI, HFBII, adhesion",
author = "Grun{\'e}r, {Mathias S.}",
year = "2015",
language = "English",
isbn = "978-951-38-8367-6",
series = "VTT Science",
publisher = "Aalto University",
number = "114",
address = "Finland",
school = "Aalto University",

}

Molecular interactions of hydrophobin proteins with their surroundings : Dissertation. / Grunér, Mathias S.

Aalto University, 2015. 110 p.

Research output: ThesisDissertationMonograph

TY - THES

T1 - Molecular interactions of hydrophobin proteins with their surroundings

T2 - Dissertation

AU - Grunér, Mathias S.

PY - 2015

Y1 - 2015

N2 - This thesis describes the properties of a group of proteins named hydro-phobins, which fulfil a variety of functions in the growth and function of filamentous fungi. Hydrophobins can be utilized as coatings/protective agents, in adhesion, in surface modifications and overall functions that require surfactant-like properties. This work is concentrated on the hydrophobins HFBI, HFBII and HFBIII expressed by Trichoderma reesei. The aims of this study were to examine in what manner hydrophobins function when interacting with their surroundings and how their surroundings affect their function. Hydrophobins were shown strongly to adhere to surfaces of varying polarity and structure by self-assembly, governed by their amphiphilic nature, and to adsorb with different orientation on hydrophilic and hydrophobic surfaces. The proteins were shown to selectively recruit other proteins and molecules to a self-assembled amphiphilic film of hydrophobin. HFBI variants bound to a surface were shown to recruit T. reesei enzymes specifically depending on localized protein surface charge on the hydrophilic part of the protein, and HFBII adsorbed on nanoparticles was shown to bind layers of human plasma proteins in different manner when adsorbed on nanoparticles of varying polarity. Surface films formed by hydrophobins were shown to be highly elastic, and charged residues on the side of the proteins were shown to have a role in stabilizing the protein films formed. The surroundings in which the proteins exist were shown to also affect their function. Surfaces of varying polarity in the protein surroundings affected how they self-assemble, and hydrophobin multimer exchange in solution was shown to be governed by hydrophobic interactions and the multimer exchange behaviour was shown to be affected by other proteins and molecules. HFBII and HFBI were shown to interact in solution, altering multimer kinetics and thermodynamics considerably. Solution association methods, surface characterization analysis methods and size measurement techniques such as stopped-flow spectroscopy, quartz crystal microbalance with dissipation and differential centrifugal sedimentation were used. The results presented here show that hydrophobins function by selectively interacting with their surroundings assembled at various interfaces specifically recruiting other proteins and molecules and that the surroundings in which the proteins exist also affects their function in terms of multimer exchange behaviour and surface adhesion properties. The knowledge learned here regarding hydrophobins, show that these proteins can be specialized to function as highly selective self-assembling building blocks in applications such as biosensors and biocompatible coatings, and gives new insight in the growth and function of filamentous fungi.

AB - This thesis describes the properties of a group of proteins named hydro-phobins, which fulfil a variety of functions in the growth and function of filamentous fungi. Hydrophobins can be utilized as coatings/protective agents, in adhesion, in surface modifications and overall functions that require surfactant-like properties. This work is concentrated on the hydrophobins HFBI, HFBII and HFBIII expressed by Trichoderma reesei. The aims of this study were to examine in what manner hydrophobins function when interacting with their surroundings and how their surroundings affect their function. Hydrophobins were shown strongly to adhere to surfaces of varying polarity and structure by self-assembly, governed by their amphiphilic nature, and to adsorb with different orientation on hydrophilic and hydrophobic surfaces. The proteins were shown to selectively recruit other proteins and molecules to a self-assembled amphiphilic film of hydrophobin. HFBI variants bound to a surface were shown to recruit T. reesei enzymes specifically depending on localized protein surface charge on the hydrophilic part of the protein, and HFBII adsorbed on nanoparticles was shown to bind layers of human plasma proteins in different manner when adsorbed on nanoparticles of varying polarity. Surface films formed by hydrophobins were shown to be highly elastic, and charged residues on the side of the proteins were shown to have a role in stabilizing the protein films formed. The surroundings in which the proteins exist were shown to also affect their function. Surfaces of varying polarity in the protein surroundings affected how they self-assemble, and hydrophobin multimer exchange in solution was shown to be governed by hydrophobic interactions and the multimer exchange behaviour was shown to be affected by other proteins and molecules. HFBII and HFBI were shown to interact in solution, altering multimer kinetics and thermodynamics considerably. Solution association methods, surface characterization analysis methods and size measurement techniques such as stopped-flow spectroscopy, quartz crystal microbalance with dissipation and differential centrifugal sedimentation were used. The results presented here show that hydrophobins function by selectively interacting with their surroundings assembled at various interfaces specifically recruiting other proteins and molecules and that the surroundings in which the proteins exist also affects their function in terms of multimer exchange behaviour and surface adhesion properties. The knowledge learned here regarding hydrophobins, show that these proteins can be specialized to function as highly selective self-assembling building blocks in applications such as biosensors and biocompatible coatings, and gives new insight in the growth and function of filamentous fungi.

KW - hydrophobin

KW - self-assembly

KW - HFBI

KW - HFBII

KW - adhesion

M3 - Dissertation

SN - 978-951-38-8367-6

T3 - VTT Science

PB - Aalto University

ER -