Adsorption of Hydrophobin on Different Self-Assembled Monolayers: The Role of the Hydrophobic Dipole and the Electric Dipole

Chen, Peng; Liu, Jie; Zhao, Daohui; Jian, Zhou

doi:10.1021/la502595t

Cited by 71 publications

(106 citation statements)

References 60 publications

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“…An exception was HFB7, where preincubation failed to show any stimulation of hydrolysis by the cutinase, and it is possible that HFB7 indeed does not bind to PET. A refined explanation for the stimulatory effect of hydrophobins on PET hydrolysis by cutinase may be offered by the recent data of Peng et al (30), who showed that the T. reesei hydrophobin HFB1 (class II) adsorbs to a hydrophobic surface through its hydrophobic patch and adopts a nearly vertical hydrophobic dipole relative to the surface. If such an orientation would also occur on PET, the hydrophobins could physically interact with the cutinases, while leaving enough surface of the polymer for cutinase binding.…”

Section: Discussionmentioning

confidence: 99%

Enhanced Cutinase-Catalyzed Hydrolysis of Polyethylene Terephthalate by Covalent Fusion to Hydrophobins

Ribitsch

Acero

Przylucka

et al. 2015

Appl Environ Microbiol

160

102

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g Cutinases have shown potential for hydrolysis of the recalcitrant synthetic polymer polyethylene terephthalate (PET). We have shown previously that the rate of this hydrolysis can be enhanced by the addition of hydrophobins, small fungal proteins that can alter the physicochemical properties of surfaces. Here we have investigated whether the PET-hydrolyzing activity of a bacterial cutinase from Thermobifida cellulosilytica (Thc_Cut1) would be further enhanced by fusion to one of three Trichoderma hydrophobins, i.e., the class II hydrophobins HFB4 and HFB7 and the pseudo-class I hydrophobin HFB9b. The fusion enzymes exhibited decreased k cat values on soluble substrates (p-nitrophenyl acetate and p-nitrophenyl butyrate) and strongly decreased the hydrophilicity of glass but caused only small changes in the hydrophobicity of PET. When the enzyme was fused to HFB4 or HFB7, the hydrolysis of PET was enhanced >16-fold over the level with the free enzyme, while a mixture of the enzyme and the hydrophobins led only to a 4-fold increase at most. Fusion with the non-class II hydrophobin HFB9b did not increase the rate of hydrolysis over that of the enzyme-hydrophobin mixture, but HFB9b performed best when PET was preincubated with the hydrophobins before enzyme treatment. The pattern of hydrolysis by the fusion enzymes differed from that of Thc_Cut1 as the concentration of the product mono(2-hydroxyethyl) terephthalate relative to that of the main product, terephthalic acid, increased. Small-angle X-ray scattering (SAXS) analysis revealed an increased scattering contrast of the fusion proteins over that of the free proteins, suggesting a change in conformation or enhanced protein aggregation. Our data show that the level of hydrolysis of PET by cutinase can be significantly increased by fusion to hydrophobins. The data further suggest that this likely involves binding of the hydrophobins to the cutinase and changes in the conformation of its active center. P olyethylene terephthalate (PET) is the best-known and most widespread synthetic polyester in the world. It is used for foils and bottles as well as for fibers for the textile industry (1). Recycling of PET and modification of its properties for different applications by traditional procedures involve harsh chemical and physicochemical treatments (2, 3). Enzymatic modification, particularly by cutinases, has been recognized as a powerful alternative in the past decade (4, 5) and, besides offering new avenues for PET recycling, has the additional advantage of creating a modified PET with increased dyeing efficacy and improved binding to polyvinyl chloride without altering the polymer's bulk properties (4, 5).On the other hand, enzymatic hydrolysis of PET has the inherent disadvantage of occurring at a very low rate (5, 6). The reasons for this are not yet clearly understood. The access of the active center of the cutinase to the insoluble substrate is apparently one of the rate-limiting points, because enlarging the areas around the active sites of cutinases from Fus...

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Section: Discussionmentioning

confidence: 99%

Enhanced Cutinase-Catalyzed Hydrolysis of Polyethylene Terephthalate by Covalent Fusion to Hydrophobins

Ribitsch

Acero

Przylucka

et al. 2015

Appl Environ Microbiol

160

102

View full text Add to dashboard Cite

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“…43,51 For PTMC simulations, N replicas were parallel simulated, each in the canonical ensemble with a different temperature T. Details were the same as interpreted in our previous studies. [43][44][45]50,52 The MC simulation in each replica was carried out in a box of 150 Â 150 Â 150 Å 3 . The protein was initially put 75 Å above the model surface with a random orientation, and then the protein was translated and rotated around its centre of mass during simulations.…”

Section: Ptmc Simulation Detailsmentioning

confidence: 99%

“…Peng et al 50 adopted the hydrophobic dipole to study hydrophobin adsorption on different SAMs and implied that the hydrophobic dipole may be applied to predict the probable orientations of a protein adsorbed on a hydrophobic surface. Lipase adsorption on surfaces with varying polarity has been explored experimentally and theoretically.…”

Section: View Article Onlinementioning

confidence: 99%

“…497 D) followed by a slightly smaller value of 489 D on the COOH-SAM surface; whereas the bulk phase has a smallest dipole moment of 466 D. This is a result of structural rearrangement exerted by the electric fields of charged surfaces, which also supports that a larger dipole moment favors a narrower orientation distribution just as shown in our simulations and previous studies. 50,58 The RMSF, as a function of the residue number, is an indicator of flexibility of a protein adsorbed on a surface with respect to the free protein. It was calculated from the trajectory data after RMSD converged in different systems and is shown in Fig.…”

Section: Conformation Stabilitymentioning

confidence: 99%

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Lipase adsorption on different nanomaterials: a multi-scale simulation study

Zhao

Chen

Jian

2015

Phys. Chem. Chem. Phys.

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Candida antarctica lipase B (CalB) is an efficient biocatalyst for hydrolysis and esterification, which plays an important role in the production of biodiesel in the bioenergy industries. The ordered immobilisation of lipases on different supports would be significant for its enzymatic catalysis in some biodiesel production processes; however, the underlying mechanisms and the preferred lipase orientation are not well understood yet. In this work, a fundamental understanding of the orientation and adsorption mechanism of lipase on four different nanomaterial surfaces with different surface chemistry are explored in detail by a combination of parallel tempering Monte Carlo (PTMC) and molecular dynamics (MD) simulations. Simulation results show that lipase is strongly adsorbed onto the hydrophobic graphite surface, as reflected by the large contact area and interaction energy; while the adsorption onto the hydrophilic TiO2 surface is weak due to two strongly adhered water layers; meanwhile lipase undergoes desorption and reorientation processes. For CalB adsorption on positively and negatively charged surfaces (NH2-SAM and COOH-SAM), the orientation distributions of lipase are narrow, and opposite orientations are obtained. CalB adsorbed on NH2-SAM has its catalytic centre oriented towards the surface, which is not conducive to the substrate binding; while the catalytic centre faces toward the solution when it is adsorbed on the COOH-SAM. Besides, the native structures of CalB adsorbed on different surfaces are preserved, which indicates lipase as a robust enzyme. The simulation results will promote our understanding on how surface properties of nanomaterials, such as charge or hydrophobicity, will affect lipase immobilisation, and help us in the rational design and development of immobilised lipase carriers.

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“…Due to their unique properties, hydrophobins have become attractive for use in several types of biotechnical applications. These include stabilization of colloidal dispersions, reverse the wettability of surfaces, dispersion of insoluble drug compounds, production of stable foams, and protein immobilization [8, 10–13]. Hydrophobins are very soluble in water up to 100 mg/mL and display unusual detergent-like behaviour in solution as they form different kinds of oligomers, depending on the conditions and on the hydrophobin type [9, 14, 15].…”

Section: Introductionmentioning

confidence: 99%

Induced Fit in Protein Multimerization: The HFBI Case

Riccardi

Mereghetti

2016

PLoS Comput Biol

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Hydrophobins, produced by filamentous fungi, are small amphipathic proteins whose biological functions rely on their unique surface-activity properties. Understanding the mechanistic details of the multimerization process is of primary importance to clarify the interfacial activity of hydrophobins. We used free energy calculations to study the role of a flexible β-hairpin in the multimerization process in hydrophobin II from Trichoderma reesei (HFBI). We characterized how the displacement of this β-hairpin controls the stability of the monomers/dimers/tetramers in solution. The regulation of the oligomerization equilibrium of HFBI will necessarily affect its interfacial properties, fundamental for its biological function and for technological applications. Moreover, we propose possible routes for the multimerization process of HFBI in solution. This is the first case where a mechanism by which a flexible loop flanking a rigid patch controls the protein-protein binding equilibrium, already known for proteins with charged binding hot-spots, is described within a hydrophobic patch.

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Adsorption of Hydrophobin on Different Self-Assembled Monolayers: The Role of the Hydrophobic Dipole and the Electric Dipole

Cited by 71 publications

References 60 publications

Enhanced Cutinase-Catalyzed Hydrolysis of Polyethylene Terephthalate by Covalent Fusion to Hydrophobins

Enhanced Cutinase-Catalyzed Hydrolysis of Polyethylene Terephthalate by Covalent Fusion to Hydrophobins

Lipase adsorption on different nanomaterials: a multi-scale simulation study

Induced Fit in Protein Multimerization: The HFBI Case

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