Prokaryotic expression, purification, and polyclonal antibody production of a hydrophobin from Grifola frondosa

A new hydrophobin candidate from Cladosporium macrocarpum with super-hydrophobic surface

Hydrophobins are amphipathic proteins with small molecular weights produced in filamentous fungi. These proteins are highly stable due to the disulfide bonds formed between the protected cysteine residues. They have great potential for usage in many different fields such as surface modifications, tissue engineering, and drug transport systems because hydrophobins are surfactants and soluble in harsh mediums. In this study, it was aimed to determine the hydrophobin proteins responsible for the hydrophobicity of the super-hydrophobic fungi isolates in the culture medium and to carry out the molecular characterization of the hydrophobin producer species. As a result of measuring surface hydrophobicity by determining the water contact angle, five different fungi with the highest hydrophobicity were classified as Cladosporium by classical and molecular (ITS and D1-D2 regions) methods. Also, protein extraction according to the recommended method for obtaining hydrophobins from spores of these Cladosporium species indicated that the isolates have similar protein profiles. Ultimately, the isolate named A5 with the highest water contact angle was identified as Cladosporium macrocarpum, and the 7 kDa band was appointed as a hydrophobin since it was the most abundant protein in protein extraction for this species.

Soluble Expression and Efficient Purification of Recombinant Class I Hydrophobin DewA

Hydrophobins are small proteins (<20 kDa) with an amphipathic tertiary structure that are secreted by various filamentous fungi. Their amphipathic properties provide surfactant-like activity, leading to the formation of robust amphipathic layers at hydrophilic–hydrophobic interfaces, which make them useful for a wide variety of industrial fields spanning protein immobilization to surface functionalization. However, the industrial use of recombinant hydrophobins has been hampered due to low yield from inclusion bodies owing to the complicated process, including an auxiliary refolding step. Herein, we report the soluble expression of a recombinant class I hydrophobin DewA originating from Aspergillus nidulans, and its efficient purification from recombinant Escherichia coli. Soluble expression of the recombinant hydrophobin DewA was achieved by a tagging strategy using a systematically designed expression tag (ramp tag) that was fused to the N-terminus of DewA lacking the innate signal sequence. Highly expressed recombinant hydrophobin DewA in a soluble form was efficiently purified by a modified aqueous two-phase separation technique using isopropyl alcohol. Our approach for expression and purification of the recombinant hydrophobin DewA in E. coli shed light on the industrial production of hydrophobins from prokaryotic hosts.

Class I hydrophobins pretreatment stimulates PETase for monomers recycling of waste PETs

Poly(ethylene terephthalate) hydrolase (PETase) from Ideonella sakaiensis 201-F6 was expressed and purified from Escherichia coli to hydrolyze poly(ethylene terephthalate) (PET) fibers waste for its monomers recycling. Hydrolysis carried out at pH 8 and 30 °C was found to be the optimal condition based on measured monomer mono(2-hydroxyethyl) terephthalate (MHET) and terephthalic acid (TPA) concentrations after 24 h reaction. The intermediate product bis(2-hydroxyethyl) terephthalate (BHET) was a good substrate for PETase because BHET released from PET hydrolysis was efficiently converted into MHET. Only a trace amount of MHET could be further hydrolyzed to TPA. Class I hydrophobins RolA from Aspergillus oryzae and HGFI from Grifola frondosa were expressed and purified from E. coli to pretreat PET surface for accelerating PETase hydrolysis against PET. The weight loss of hydrolyzed PET increased from approximately 18% to 34% after hydrophobins pretreatment. The releases of TPA and MHET from HGFI-pretreated PET were enhanced 48% and 62%, respectively. The selectivity (TPA/MHET ratio) of the hydrolysis reaction was approximately 0.5.

Effect of gene copy number and chaperone coexpression on recombinant hydrophobin HFBI biosurfactant production in Pichia pastoris

Hydrophobins are small highly surface-active fungal proteins with potential as biosurfactants in a wide array of applications. However, practical implementation of hydrophobins at large scale has been hindered by low recombinant yields. In this study, the effects of increasing hydrophobin gene copy number and overexpressing endoplasmic reticulum resident chaperone proteins Kar2p, Pdi1p, and Ero1p were explored as a means to enhance recombinant yields of the class II hydrophobin HFBI in the eukaryotic expression host Pichia pastoris. One-, 2-, and 3-copy-HFBI strains were attained using an in vitro multimer ligation approach, with strains displaying copy number stability following subsequent transformations as measured by quantitative polymerase chain reaction. Increasing HFBI copy number alone had no effect on increasing HFBI secretion, but increasing copy number in concert with chaperone overexpression synergistically increased HFBI secretion. Overexpression of PDI1 or ERO1 caused insignificant changes in HFBI secretion in 1- and 2-copy strains, but a statistically significant HFBI secretion increase in 3-copy strain. KAR2 overexpression consistently resulted in enhanced HFBI secretion in all copy number strains, with 3-copy-HFBI secreting 22±1.6 fold more than the 1-copy-HFBI/no chaperone strain. The highest increase was seen in 3-copy-HFBI/Ero1p overexpressing strain with 30±4.0 fold increase in HFBI secretion over 1-copy-HFBI/no chaperone strain. This corresponded to an expression level of approximately 330 mg/L HFBI in the 5 ml small-scale format used in this study.

Hydrophobins: multifunctional biosurfactants for interface engineering

Hydrophobins are highly surface-active proteins that have versatile potential as agents for interface engineering. Due to the large and growing number of unique hydrophobin sequences identified, there is growing potential to engineer variants for particular applications using protein engineering and other approaches. Recent applications and advancements in hydrophobin technologies and production strategies are reviewed. The application space of hydrophobins is large and growing, including hydrophobic drug solubilization and delivery, protein purification tags, tools for protein and cell immobilization, antimicrobial coatings, biosensors, biomineralization templates and emulsifying agents. While there is significant promise for their use in a wide range of applications, developing new production strategies is a key need to improve on low recombinant yields to enable their use in broader applications; further optimization of expression systems and yields remains a challenge in order to use designed hydrophobin in commercial applications.

Recombinant α-actinin subunit antigens of Trichomonas vaginalis as potential vaccine candidates in protecting against trichomoniasis

Background

Human trichomoniasis caused by Trichomonas vaginalis is one of the most common sexually transmitted diseases with more than 200 million cases worldwide. It has caused a series of health problems to patients. For prevention and control of infectious diseases, vaccines are usually considered as one of the most cost-efficient tools. However, until now, work on the development of T. vaginalis vaccines is still mainly focused on the screening of potential immunogens. Alpha-actinin characterized by high immunogenicity in T. vaginalis was suggested as a promising candidate. Therefore, the purpose of this study was to evaluate the protective potency of recombinant α-actinin against T. vaginalis infection in a mouse intraperitoneal model.

Methods

Two selected coding regions of α-actinin (ACT-F, 14–469 aa and ACT-T, 462–844 aa) amplified from cDNA were cloned into pET-32a (+) expression vector and transfected into BL21 cells. After induction with IPTG and purification with electroelution, the two recombinant fusion proteins were emulsified in Freund’s adjuvant (FA) and used to immunize BALB/C mice. Following intraperitoneal inoculation with T. vaginalis, the survival rate of mice was monitored for the assessment of protective potency. After immunization, the antibody level in mouse serum was assessed by ELISA, splenocyte proliferation response was detected with CCK8 and cytokines in the supernatant of splenocytes were quantified with a cytometric bead-based assay.

Results

We successfully obtained purified ACT-F (70.33 kDa) and ACT-T (61.7kDa). Both recombinant proteins could provide significant protection against T. vaginalis challenge, especially ACT-T (with 100% protection within one month). Meanwhile, high levels of specific total IgG and subtypes (IgG1 > IgG2a) were detected in sera from the immunized mice. Our results also revealed a statistically significant increase in splenocyte proliferation and related cytokine (IFN-γ, IL-6, IL-17A and IL-10) production after repeated stimulation with the corresponding antigens in vitro.

Conclusions

Immunization with both ACT-F and ACT-T could confer partial to complete protection and trigger strong Th1/Th2 mixed humoral and cellular immune responses in the mouse host. This suggested that recombinant α-actinin subunit antigens may be promising vaccine candidates against trichomoniasis.

Expression, purification and production of antisera against recombinant truncated VP22 protein

Cell-penetrating peptides (CPPs) are non-invasive vectors that can efficiently transport bioactive cargo across the cell membrane. Naturally occurring CPPs, such as the tegument protein VP22 of the Herpes simplex virus type 1, can potentiate protein-drug delivery into living cells. The aim of the present study was to construct anti-VP22 antibodies that can be used to detect VP22-fusion drugs. Therefore, 60- and 45-amino acid peptides corresponding to the N-terminus and C-terminus of VP22, respectively, were cloned, expressed and purified. Subsequently, polyclonal antisera against them were generated. The DNA sequence, cloned into the pGEX-5X-1 vector, was transformed into E. coli BL21 (DE3). After inducing expression with 1 mM isopropyl-β-d-thiogalactopyranoside (IPTG) at 25°C for 4 h, the recombinant VP22 proteins were purified by electroelution. The high titers of polyclonal antisera obtained subsequent to immunization of mice with the purified recombinant truncated VP22 was confirmed by ELISA. Western blot and immunofluorescence analysis showed that the antisera detected both the truncated and full-length VP22 protein. Therefore, the polyclonal antisera against VP22 may be used in the detection of the intracellular location of VP22-fusion protein drugs.