The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Han A. B. Wösten - One of the best experts on this subject based on the ideXlab platform.
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repellents have functionally replaced Hydrophobins in mediating attachment to a hydrophobic surface and in formation of hydrophobic aerial hyphae in ustilago maydis
Microbiology, 2006Co-Authors: Wieke R Teertstra, Heine J Deelstra, Miroslav Vranes, Ralph Bohlmann, Regine Kahmann, Jorg Kamper, Han A. B. WöstenAbstract:Ustilago maydis contains one repellent and two class I Hydrophobin genes in its genome. The repellent gene rep1 has been described previously. It encodes 11 secreted repellent peptides that result from the cleavage of a precursor protein at KEX2 recognition sites. The Hydrophobin gene hum2 encodes a typical class I Hydrophobin of 117 aa, while hum3 encodes a Hydrophobin that is preceded by 17 repeat sequences. These repeats are separated, like the repellent peptides, by KEX2 recognition sites. Gene hum2, but not hum3, was shown to be expressed in a cross of two compatible wild-type strains, suggesting a role of the former Hydrophobin gene in aerial hyphae formation. Indeed, aerial hyphae formation was reduced in a Δhum2 cross. However, the reduction in aerial hyphae formation was much more dramatic in the Δrep1 cross. Moreover, colonies of the Δrep1 cross were completely wettable, while surface hydrophobicity was unaffected and only slightly reduced in the Δhum2 and the Δhum2Δhum3 cross, respectively. It was also shown that the repellents and not the Hydrophobins are involved in attachment of hyphae to hydrophobic Teflon. Deleting either or both Hydrophobin genes in the Δrep1 strains did not further affect aerial hyphae formation, surface hydrophobicity and attachment. From these data it is concluded that Hydrophobins of U. maydis have been functionally replaced, at least partially, by repellents.
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Interaction and Comparison of a Class I Hydrophobin from Schizophyllum commune and Class II Hydrophobins from Trichoderma reesei
Biomacromolecules, 2006Co-Authors: Sanna Askolin, Markus Linder, Merja Penttilä, Karin Scholtmeijer, Marcel L. De Vocht, Maija Tenkanen, Han A. B. WöstenAbstract:Hydrophobins fulfill a wide spectrum of functions in fungal growth and development. These proteins self-assemble at hydrophilic-hydrophobic interfaces into amphipathic membranes. Hydrophobins are divided into two classes based on their hydropathy patterns and solubility. We show here that the properties of the class II Hydrophobins HFBI and HFBII of Trichoderma reesei differ from those of the class I Hydrophobin SC3 of Schizophyllum commune. In contrast to SC3, self-assembly of HFBI and HFBII at the water-air interface was neither accompanied by a change in secondary structure nor by a change in ultrastructure. Moreover, maximal lowering of the water surface tension was obtained instantly or took several minutes in the case of HFBII and HFBI, respectively. In contrast, it took several hours in the case of SC3. Oil emulsions prepared with HFBI and SC3 were more stable than those of HFBII, and HFBI and SC3 also interacted more strongly with the hydrophobic Teflon surface making it wettable. Yet, the HFBI coating did not resist treatment with hot detergent, while that of SC3 remained unaffected. Interaction of all the Hydrophobins with Teflon was accompanied with a change in the circular dichroism spectra, indicating the formation of an alpha-helical structure. HFBI and HFBII did not affect self-assembly of the class I Hydrophobin SC3 of S. commune and vice versa. However, precipitation of SC3 was reduced by the class II Hydrophobins, indicating interaction between the assemblies of both classes of Hydrophobins.
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promotion of fibroblast activity by coating with Hydrophobins in the β sheet end state
Biomaterials, 2004Co-Authors: Meike Janssen, M. B. M. Van Leeuwen, Van Theo Kooten, De Jacob Vries, Lubbert Dijkhuizen, Han A. B. WöstenAbstract:Abstract Hydrophobins such as SC3 and SC4 of Schizophyllum commune self-assemble into an amphipathic film at hydrophilic/hydrophobic interfaces. These proteins can thus change the nature of surfaces, which makes them attractive candidates to improve physio– and physico–chemical properties of implant surfaces. At a hydrophobic solid, assembly of the Hydrophobin is arrested in an intermediate state, called the α -helical state. The conversion to the stable β -sheet end state can be induced by treating the solid at elevated temperatures in the presence of detergent. We here show that SC3 and SC4 in the α -helical state homogeneously cover Teflon sheets when coating was performed at 20°C. However, when the protein was adsorbed at 80°C aggregates were shown to bind tightly to the adsorbed Hydrophobin film. The transition to the β -sheet state created pores of about 50 nm in the SC3 and SC4 coatings when coating was performed at 20°C. Cell growth and morphology on SC4 coatings was better than on SC3. In case of both Hydrophobins, fibroblast growth and morphology was not influenced by the coating temperature or the conformation of the protein. However, in contrast to the α -helical state, the β -sheet state of both SC3 and SC4 hardly, if at all, affected mitochondrial activity.
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coating with genetic engineered Hydrophobin promotes growth of fibroblasts on a hydrophobic solid
Biomaterials, 2002Co-Authors: Marleen Janssen, Karin Scholtmeijer, Van Theo Kooten, Lubbert Dijkhuizen, Van Maria Leeuwen, Han A. B. WöstenAbstract:Class I Hydrophobins self-assemble at hydrophilic-hydrophobic interfaces into a highly insoluble amphipathic film. Upon self-assembly of these fungal proteins hydrophobic solids turn hydrophilic, while hydrophilic materials can be made hydrophobic. Hydrophobins thus change the nature of a surface. This property makes them interesting candidates to improve physio- and physico-chemical properties of implant surfaces. We here show that growth of fibroblasts on Teflon can be improved by coating the solid with genetically engineered SC3 Hydrophobin. Either deleting a stretch of 25 amino acids at the N-terminus of the mature Hydrophobin (TrSC3) or fusing the RGD peptide to this end (RGD-SC3) improved growth of fibroblasts on the solid surface. In addition, we have shown that assembled SC3 and TrSC3 are not toxic when added to the medium of a cell culture of fibroblasts in amounts up to 125 microg ml(-1).
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self assembly of the Hydrophobin sc3 proceeds via two structural intermediates
Protein Science, 2002Co-Authors: Marcel L. De Vocht, Han A. B. Wösten, Joseph G. H. Wessels, Ilya Reviakine, Alain Brisson, Wolfpeter Ulrich, Wilma Bergsmaschutter, Horst Vogel, George T. RobillardAbstract:Hydrophobins self assemble into amphipathic films at hydrophobic–hydrophilic interfaces. These proteins are involved in a broad range of processes in fungal development. We have studied the conformational changes that accompany the self-assembly of the Hydrophobin SC3 with polarization-modulation infrared reflection absorption spectroscopy, attenuated total reflection Fourier transform infrared spectroscopy, and circular dichroism, and related them to changes in morphology as observed by electron microcopy. Three states of SC3 have been spectroscopically identified previously as follows: the monomeric state, the α-helical state that is formed upon binding to a hydrophobic solid, and the β-sheet state, which is formed at the air–water interface. Here, we show that the formation of the β-sheet state of SC3 proceeds via two intermediates. The first intermediate has an infrared spectrum indistinguishable from that of the α-helical state of SC3. The second intermediate is rich in β-sheet structure and has a featureless appearance under the electron microscope. The end state has the same secondary structure, but is characterized by the familiar 10-nm-wide rodlets.
Joseph G. H. Wessels - One of the best experts on this subject based on the ideXlab platform.
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Structural and Functional Role of the Disulfide Bridges in the
2016Co-Authors: Marcel L. De Vocht, Joseph G. H. Wessels, Ilya Reviakine, Han A. B. Wösten, Alain Brisson, George T. RobillardAbstract:Hydrophobins function in fungal development by self-assembly at hydrophobic-hydrophilic interfaces such as the interface between the fungal cell wall and the air or a hydrophobic solid. These proteins contain eight con-served cysteine residues that form four disulfide bonds. To study the effect of the disulfide bridges on the self-assembly, the disulfides of the SC3 Hydrophobin were reduced with 1,4-dithiothreitol. The free thiols were then blocked with either iodoacetic acid (IAA) or iodoac-etamide (IAM), introducing eight or zero negative charges, respectively. Circular dichroism and infrared spectroscopy showed that after opening of the disulfide bridges SC3 is initially unfolded. IAA-SC3 did not self-assemble at the air-water interface upon shaking an aqueous solution. Remarkably, after drying down IAA
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self assembly of the Hydrophobin sc3 proceeds via two structural intermediates
Protein Science, 2002Co-Authors: Marcel L. De Vocht, Han A. B. Wösten, Joseph G. H. Wessels, Ilya Reviakine, Alain Brisson, Wolfpeter Ulrich, Wilma Bergsmaschutter, Horst Vogel, George T. RobillardAbstract:Hydrophobins self assemble into amphipathic films at hydrophobic–hydrophilic interfaces. These proteins are involved in a broad range of processes in fungal development. We have studied the conformational changes that accompany the self-assembly of the Hydrophobin SC3 with polarization-modulation infrared reflection absorption spectroscopy, attenuated total reflection Fourier transform infrared spectroscopy, and circular dichroism, and related them to changes in morphology as observed by electron microcopy. Three states of SC3 have been spectroscopically identified previously as follows: the monomeric state, the α-helical state that is formed upon binding to a hydrophobic solid, and the β-sheet state, which is formed at the air–water interface. Here, we show that the formation of the β-sheet state of SC3 proceeds via two intermediates. The first intermediate has an infrared spectrum indistinguishable from that of the α-helical state of SC3. The second intermediate is rich in β-sheet structure and has a featureless appearance under the electron microscope. The end state has the same secondary structure, but is characterized by the familiar 10-nm-wide rodlets.
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structural and functional role of the disulfide bridges in the Hydrophobin sc3
Journal of Biological Chemistry, 2000Co-Authors: Marcel L. De Vocht, Han A. B. Wösten, Joseph G. H. Wessels, Ilya Reviakine, Alain Brisson, George T. RobillardAbstract:Hydrophobins function in fungal development by self-assembly at hydrophobic-hydrophilic interfaces such as the interface between the fungal cell wall and the air or a hydrophobic solid. These proteins contain eight conserved cysteine residues that form four disulfide bonds. To study the effect of the disulfide bridges on the self-assembly, the disulfides of the SC3 Hydrophobin were reduced with 1,4-dithiothreitol. The free thiols were then blocked with either iodoacetic acid (IAA) or iodoacetamide (IAM), introducing eight or zero negative charges, respectively. Circular dichroism and infrared spectroscopy showed that after opening of the disulfide bridges SC3 is initially unfolded. IAA-SC3 did not self-assemble at the air-water interface upon shaking an aqueous solution. Remarkably, after drying down IAA-SC3 or after exposing it to Teflon, it refolded into a structure similar to that observed for native SC3 at these interfaces. Iodoacetamide-SC3 on the other hand, which does not contain extra charges, spontaneously refolded in water in the amyloid-like β-sheet conformation, characteristic for SC3 assembled at the water-air interface. From this we conclude that the disulfide bridges of SC3 are not directly involved in self-assembly but keep Hydrophobin monomers soluble in the fungal cell or its aqueous environment, preventing premature self-assembly.
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Hydrophobins line air channels in fruiting bodies of schizophyllum commune and agaricus bisporus
Fungal Biology, 1999Co-Authors: Luis G Lugones, Han A. B. Wösten, K U Birkenkamp, Klaas A Sjollema, Jan Zagers, Joseph G. H. WesselsAbstract:The Hydrophobin SC4 was isolated from the medium of a dikaryon from Schizophyllum commune with disrupted SC3 genes. Although not glycosylated, its biophysical properties were similar to those of SC3. As the Hydrophobins SC3 from S. commune and ABH1 and ABH3 from Agaricus bisporus, SC4 self-assembled at hydrophilic-hydrophobic interfaces into an SDS insoluble amphipathic film with a typical rodlet structure at its hydrophobic face, and also proved to be a powerful surfactant. Similar rodlet structures were observed in the fruiting body plectenchyma. By immunodetection SC4 could be localized lining air channels within this tissue. A similar localization was found for the ABH1 Hydrophobin in fruiting bodies of A. bisporus. Probably, these Hydrophobin coatings prevent collapse of air channels allowing efficient gas exchange even under wet conditions.
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structural characterization of the Hydrophobin sc3 as a monomer and after self assembly at hydrophobic hydrophilic interfaces
Biophysical Journal, 1998Co-Authors: Marcel L. De Vocht, Onno M. H. Vries, Han A. B. Wösten, Joseph G. H. Wessels, Karin Scholtmeijer, Eric W Van Der Vegte, Nathalie Sonveaux, Jean Marie Ruysschaert, Georges Hadziioannou, George T. RobillardAbstract:Hydrophobins are small fungal proteins that self-assemble at hydrophilic/hydrophobic interfaces into amphipathic membranes that, in the case of Class I Hydrophobins, can be disassembled only by treatment with agents like pure trifluoroacetic acid. Here we characterize, by spectroscopic techniques, the structural changes that occur upon assembly at an air/water interface and upon assembly on a hydrophobic solid surface, and the influence of deglycosylation on these events. We determined that the Hydrophobin SC3 from Schizophyllum commune contains 16–22 O-linked mannose residues, probably attached to the N-terminal part of the peptide chain. Scanning force microscopy revealed that SC3 adsorbs specifically to a hydrophobic surface and cannot be removed by heating at 100°C in 2% sodium dodecyl sulfate. Attenuated total reflection Fourier transform infrared spectroscopy and circular dichroism spectroscopy revealed that the monomeric, water-soluble form of the protein is rich in β-sheet structure and that the amount of β-sheet is increased after self-assembly on a water-air interface. α-Helix is induced specifically upon assembly of the protein on a hydrophobic solid. We propose a model for the formation of rodlets, which may be induced by dehydration and a conformational change of the glycosylated part of the protein, resulting in the formation of an amphipathic α-helix that forms an anchor for binding to a substrate. The assembly in the β-sheet form seems to be involved in lowering of the surface tension, a potential function of Hydrophobins.
Markus Linder - One of the best experts on this subject based on the ideXlab platform.
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Hydrophobins as aqueous lubricant additive for a soft sliding contact
Colloids and Surfaces B: Biointerfaces, 2014Co-Authors: Kirsi I. Pakkanen, Markus LinderAbstract:Abstract Two type II fungal Hydrophobins, HFBI and FpHYD5, have been studied as aqueous lubricant additive at a nonpolar, compliant sliding contact (self-mated poly(dimethylsiloxane) (PDMS) contact) at two different concentrations, 0.1 mg/mL and 1.0 mg/mL. The two Hydrophobins are featured as non-glycosylated (HFBI, m.w. ca. 7 kDa) vs glycosylated (FpHYD5, m.w. ca. 10 kDa) proteins. Far UV CD spectra of the two Hydrophobins were very similar, suggesting overall structural similarity, but showed a noticeable difference according to the concentration. This is proposed to be related to the formation of multimers at 1.0 mg/mL. Despite 10-fold difference in the bulk concentration, the adsorbed masses of the Hydrophobins onto PDMS surface obtained from the two solutions (0.1 and 1.0 mg/mL) were nearly identical, suggesting that a monolayer of the Hydrophobins are formed from 0.1 mg/mL solution. PDMS–PDMS sliding interface was effectively lubricated by the Hydrophobin solutions, and showed a reduction in the coefficient of friction by as much as ca. two orders of magnitude. Higher concentration solution (1.0 mg/mL) provided a superior lubrication, particularly in low-speed regime, where boundary lubrication characteristic is dominant via ‘self-healing’ mechanism. FpHYD5 revealed a better lubrication than HFBI presumably due to the presence of glycans and improved hydration of the sliding interface. Two type II Hydrophobins function more favorably compared to a synthetic amphiphilic copolymer, PEO–PPO–PEO, with a similar molecular weight. This is ascribed to higher amount of adsorption of the Hydrophobins to hydrophobic surfaces from aqueous solution.
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identification and characterization of gushing active Hydrophobins from fusarium graminearum and related species
Journal of Basic Microbiology, 2012Co-Authors: Tuija Sarlin, Markus Linder, Teemu Kivioja, Nisse Kalkkinen, Tiina NakarisetalaAbstract:Fungal infection of barley and malt, particularly by the Fusarium species, is a direct cause of spontaneous overfoaming of beer, referred to as gushing. We have shown previously that small fungal proteins, Hydrophobins, act as gushing-inducing factors in beer. The aim of our present study was to isolate and characterize Hydrophobins from a gushing-active fungus, Fusarium graminearum (teleomorph Gibberella zeae) and related species. We generated profile hidden Markov models (profile HMMs) for the Hydrophobin classes Ia, Ib and II from the multiple sequence alignments of their known members available in public domain databases. We searched the published Fusarium graminearum genome with the Markov models. The best matching sequences and the corresponding genes were isolated from F. graminearum and the related species F. culmorum and F. poae by PCR and characterized. One each of the putative F. graminearum and F. poae Hydrophobin genes were expressed in the heterologous host Trichoderma reesei. The proteins corresponding to the genes were purified and identified as Hydrophobins and named GzHYD5 and FpHYD5, respectively. Concentrations of 0.003 ppm of these Hydrophobins were observed to induce vigorous beer gushing.
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protein hgfi from the edible mushroom grifola frondosa is a novel 8 kda class i Hydrophobin that forms rodlets in compressed monolayers
Microbiology, 2008Co-Authors: Baohua Zhang, Markus Linder, Géza R. Szilvay, Zefang Wang, Ren Sun, Janne Janis, Shuren Feng, Mingqiang QiaoAbstract:Hydrophobins are a group of low-molecular-mass, cysteine-rich proteins that have unusual biophysical properties. They are highly surface-active and can self-assemble at hydrophobic–hydrophilic interfaces, forming surface layers that are able to reverse the hydropathy of surfaces. Here we describe a novel Hydrophobin from the edible mushroom Grifola frondosa, which was named HGFI and belongs to class I. The Hydrophobin gene was identified during sequencing of random clones from a cDNA library, and the corresponding protein was isolated as a hot SDS-insoluble aggregate from the cell wall. The purified HGFI was found to have 83 amino acids. The protein sequence deduced from the cDNA sequence had 107 amino acids, from which a 24 aa signal sequence had been cleaved off in the mature protein. This signal sequence was 5 aa longer than had been predicted on the basis of signal peptide analysis of the cDNA. Rodlet mosaic structures were imaged using atomic force microscopy (AFM) on mica surfaces after drying-down HGFI solutions. Using Langmuir films we were also able to take images of both the hydrophobic and hydrophilic sides of films formed at the air–water interface. No distinct structure was observed in films compressed once, but in films compressed several times rodlet structures could be seen. Most rodlets were aligned in the same direction, indicating that formation of rodlets may be promoted during compression of the monolayer.
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Hydrophobin hfbi a potential fusion partner for one step purification of recombinant proteins from insect cells
Protein Expression and Purification, 2008Co-Authors: Tomi Lahtinen, Markus Linder, Tiina Nakarisetala, Christian OkerblomAbstract:Abstract Hydrophobins play an important role in binding and assembly of fungal surface structures as well as in medium–air interactions. These, hydrophobic properties provide interesting possibilities when purification of macromolecules is concerned. In aqueous micellar two-phase systems, based on surfactants, the water soluble Hydrophobins are concentrated inside micellar structures and, thus, distributed to defined aqueous phases. This, one-step purification is attractive particularly when large-scale production of recombinant proteins is concerned. In the present study the Hydrophobin HFBI of Trichoderma reesei was expressed as an N-terminal fusion with chicken avidin in baculovirus infected insect cells. The intracellular distribution of the recombinant fusion construct was analyzed by confocal microscopy and the protein subsequently purified from cytoplasmic extracts in an aqueous micellar two-phase system by using a non-ionic surfactant. The results show that Hydrophobin and an avidin fusion thereof were efficiently expressed in insect cells and that these hydrophobic proteins could be efficiently purified from these cells in one-step by adopting an aqueous micellar two-phase system.
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interactions of Hydrophobin proteins in solution studied by small angle x ray scattering
Biophysical Journal, 2008Co-Authors: Kaisa Kisko, Markus Linder, Géza R. Szilvay, Ulla Vainio, Ritva SerimaaAbstract:Hydrophobins are a group of very surface-active, fungal proteins known to self-assemble on various hydrophobic/hydrophilic interfaces. The self-assembled films coat fungal structures and mediate their attachment to surfaces. Hydrophobins are also soluble in water. Here, the association of Hydrophobins HFBI and HFBII from Trichoderma reesei in aqueous solution was studied using small-angle x-ray scattering. Both HFBI and HFBII exist mainly as tetramers in solution in the concentration range 0.5–10 mg/ml. The assemblies of HFBII dissociate more easily than those of HFBI, which can tolerate changes of pH from 3 to 9 and temperatures in the range 5°C–60°C. The self-association of HFBI and HFBII is mainly driven by the hydrophobic effect, and addition of salts along the Hofmeister series promotes the formation of larger assemblies, whereas ethanol breaks the tetramers into monomers. The possibility that the oligomers in solution form the building blocks of the self-assembled film at the air/water interface is discussed.
Margaret Sunde - One of the best experts on this subject based on the ideXlab platform.
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self assembly of mpg1 a Hydrophobin protein from the rice blast fungus that forms functional amyloid coatings occurs by a surface driven mechanism
Scientific Reports, 2016Co-Authors: Chi L.l. Pham, Anthony A. Rey, Qin Ren, A K H Kwan, Margaux Soules, Georg Meisl, Tuomas P J Knowles, Margaret SundeAbstract:Rice blast is a devastating disease of rice caused by the fungus Magnaporthe oryzae and can result in loss of a third of the annual global rice harvest. Two Hydrophobin proteins, MPG1 and MHP1, are highly expressed during rice blast infections. These Hydrophobins have been suggested to facilitate fungal spore adhesion and to direct the action of the enzyme cutinase 2, resulting in penetration of the plant host. Therefore a mechanistic understanding of the self-assembly properties of these Hydrophobins and their interaction with cutinase 2 is crucial for the development of novel antifungals. Here we report details of a study of the structure, assembly and interactions of these proteins. We demonstrate that, in vitro, MPG1 assembles spontaneously into amyloid structures while MHP1 forms a non-fibrillar film. The assembly of MPG1 only occurs at a hydrophobic:hydrophilic interface and can be modulated by MHP1 and other factors. We further show that MPG1 assemblies can much more effectively retain cutinase 2 activity on a surface after co-incubation and extensive washing compared with other protein coatings. The assembly and interactions of MPG1 and MHP1 at hydrophobic surfaces thereby provide the basis for a possible mechanism by which the fungus can develop appropriately at the infection interface.
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Fungal Hydrophobin Proteins Produce Self-Assembling Protein Films with Diverse Structure and Chemical Stability.
Nanomaterials (Basel Switzerland), 2014Co-Authors: Qin Ren, Ann H. Kwan, Chi L.l. Pham, Vanessa K. Morris, Margaret SundeAbstract:Hydrophobins are small proteins secreted by fungi and which spontaneously assemble into amphipathic layers at hydrophilic-hydrophobic interfaces. We have examined the self-assembly of the Class I Hydrophobins EAS∆15 and DewA, the Class II Hydrophobin NC2 and an engineered chimeric Hydrophobin. These Class I Hydrophobins form layers composed of laterally associated fibrils with an underlying amyloid structure. These two Class I Hydrophobins, despite showing significant conformational differences in solution, self-assemble to form fibrillar layers with very similar structures and require a hydrophilic-hydrophobic interface to trigger self-assembly. Addition of additives that influence surface tension can be used to manipulate the fine structure of the protein films. The Class II Hydrophobin NC2 forms a mesh-like protein network and the engineered chimeric Hydrophobin displays two multimeric forms, depending on assembly conditions. When formed on a graphite surface, the fibrillar EAS∆15 layers are resistant to alcohol, acid and basic washes. In contrast, the NC2 Class II monolayers are dissociated by alcohol treatment but are relatively stable towards acid and base washes. The engineered chimeric Class I/II Hydrophobin shows increased stability towards alcohol and acid and base washes. Self-assembled Hydrophobin films may have extensive applications in biotechnology where biocompatible; amphipathic coatings facilitate the functionalization of nanomaterials.
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solution structure and interface driven self assembly of nc2 a new member of the class ii Hydrophobin proteins
Proteins, 2014Co-Authors: Qin Ren, Ann H. Kwan, Margaret SundeAbstract:Hydrophobins are fungal proteins that self-assemble spontaneously to form amphipathic monolayers at hydrophobic:hydrophilic interfaces. Hydrophobin assemblies facilitate fungal transitions between wet and dry environments and interactions with plant and animal hosts. NC2 is a previously uncharacterized Hydrophobin from Neurospora crassa. It is a highly surface active protein and is able to form protein layers on a water:air interface that stabilize air bubbles. On a hydrophobic substrate, NC2 forms layers consisting of an ordered network of protein molecules, which dramatically decrease the water contact angle. The solution structure and dynamics of NC2 have been determined using nuclear magnetic resonance spectroscopy. The structure of this protein displays the same core fold as observed in other Hydrophobin structures determined to date, including the Class II Hydrophobins HFBI and HFBII from Trichoderma reesei, but certain features illuminate the structural differences between Classes I and II Hydrophobins and also highlight the variations between structures of Class II Hydrophobin family members. The unique properties of Hydrophobins have attracted much attention for biotechnology applications. The insights obtained through determining the structure, biophysical properties and assembly characteristics of NC2 will facilitate the development of Hydrophobin-based applications.
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analysis of the structure and conformational states of dewa gives insight into the assembly of the fungal Hydrophobins
Journal of Molecular Biology, 2013Co-Authors: Vanessa K. Morris, Ann H. Kwan, Margaret SundeAbstract:The Hydrophobin DewA from the fungus Aspergillus nidulans is a highly surface-active protein that spontaneously self-assembles into amphipathic monolayers at hydrophobic:hydrophilic interfaces. These monolayers are composed of fibrils that are a form of functional amyloid. While there has been significant interest in the use of DewA for a variety of surface coatings and as an emulsifier in biotechnological applications, little is understood about the structure of the protein or the mechanism of self-assembly. We have solved the solution NMR structure of DewA. While the pattern of four disulfide bonds that is a defining feature of Hydrophobins is conserved, the arrangement and composition of secondary-structure elements in DewA are quite different to what has been observed in other Hydrophobin structures. In addition, we demonstrate that DewA populates two conformations in solution, both of which are assembly competent. One conformer forms a dimer at high concentrations, but this dimer is off-pathway to fibril formation and may represent an assembly control mechanism. These data highlight the structural differences between fibril-forming Hydrophobins and those that form amorphous monolayers. This work will open up new opportunities for the engineering of Hydrophobins with novel biotechnological applications.
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solid state nmr spectroscopy of functional amyloid from a fungal Hydrophobin a well ordered β sheet core amidst structural heterogeneity
Angewandte Chemie, 2012Co-Authors: Vanessa K. Morris, Margaret Sunde, Rasmus Linser, Karyn L Wilde, Anthony P Duff, Ann H. KwanAbstract:GrEASy fibrils: Hydrophobins are fungal proteins that assemble into an amphipathic fibrillar monolayer with amyloid properties and a hydrophobic face as water-resistant as Teflon. Solid-state NMR studies on EAS Hydrophobin fibrils reveal direct evidence of a partial molecular rearrangement on assembly and an ordered β-sheet-rich core in the context of a whole protein in this functional amyloid.
John R. P. Webster - One of the best experts on this subject based on the ideXlab platform.
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impact of the degree of ethoxylation of the ethoxylated polysorbate nonionic surfactant on the surface self assembly of Hydrophobin ethoxylated polysorbate surfactant mixtures
Langmuir, 2014Co-Authors: Jeff Penfold, Nick Hedges, Peixun Li, Jordan T. Petkov, I. Tucker, Robert K. Thomas, John R. P. Webster, Maximilian W. A. SkodaAbstract:Neutron reflectivity measurements have been used to study the surface adsorption of the polyethylene sorbitan monostearate surfactant, with degrees of ethoxylation varying from 3 to 20 ethylene oxide groups, with the globular protein Hydrophobin. The surface interaction between the ethoxylated polysorbate nonionic surfactants and the Hydrophobin results in self-assembly at the air–solution interface in the form of a well-defined layered surface structure. The surface interaction arises from a combination of the hydrophobic interaction between the surfactant alkyl chain and the hydrophobic patch on the surface of the Hydrophobin, and the hydrophilic interaction between the ethoxylated sorbitan headgroup and the hydrophilic regions on the surface of the Hydrophobin. The results presented show that varying the degree of ethoxylation of the polysorbate surfactant changes the interaction between the surfactant and the Hydrophobin and the packing, and hence the evolution in the resulting surface structure. The ...
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spontaneous surface self assembly in protein surfactant mixtures interactions between Hydrophobin and ethoxylated polysorbate surfactants
Journal of Physical Chemistry B, 2014Co-Authors: I. Tucker, Nick Hedges, Peixun Li, Jeff Penfold, Jordan T. Petkov, Robert K. Thomas, John R. P. WebsterAbstract:The synergistic interactions between certain ethoxylated polysorbate nonionic surfactants and the protein Hydrophobin result in spontaneous self-assembly at the air–water interface to form layered surface structures. The surface structures are characterized using neutron reflectivity. The formation of the layered surface structures is promoted by the hydrophobic interaction between the polysorbate alkyl chain and the hydrophobic patch on the surface of the globular Hydrophobin and the interaction between the ethoxylated sorbitan headgroup and hydrophilic regions of the protein. The range of the ethoxylated polysorbate concentrations over which the surface ordering occurs is a maximum for the more hydrophobic surfactant polyoxyethylene(8) sorbitan monostearate. The structures at the air–water interface are accompanied by a profound change in the wetting properties of the solution on hydrophobic substrates. In the absence of the polysorbate surfactant, Hydrophobin wets a hydrophobic surface, whereas the hyd...
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spontaneous surface self assembly in protein surfactant mixtures interactions between Hydrophobin and ethoxylated polysorbate surfactants
Journal of Physical Chemistry B, 2014Co-Authors: I. Tucker, Nick Hedges, Jeff Penfold, Jordan T. Petkov, Robert K. Thomas, Andrew Richard Cox, John R. P. WebsterAbstract:The synergistic interactions between certain ethoxylated polysorbate nonionic surfactants and the protein Hydrophobin result in spontaneous self-assembly at the air-water interface to form layered surface structures. The surface structures are characterized using neutron reflectivity. The formation of the layered surface structures is promoted by the hydrophobic interaction between the polysorbate alkyl chain and the hydrophobic patch on the surface of the globular Hydrophobin and the interaction between the ethoxylated sorbitan headgroup and hydrophilic regions of the protein. The range of the ethoxylated polysorbate concentrations over which the surface ordering occurs is a maximum for the more hydrophobic surfactant polyoxyethylene(8) sorbitan monostearate. The structures at the air-water interface are accompanied by a profound change in the wetting properties of the solution on hydrophobic substrates. In the absence of the polysorbate surfactant, Hydrophobin wets a hydrophobic surface, whereas the Hydrophobin/ethoxylated polysorbate mixtures where multilayer formation occurs result in a significant dewetting of hydrophobic surfaces. The spontaneous surface self-assembly for Hydrophobin/ethoxylated polysorbate surfactant mixtures and the changes in surface wetting properties provide a different insight into protein-surfactant interactions and potential for manipulating surface and interfacial properties and protein surface behavior.
