Lung cancer is the most lethal malignancies with high aggressive and poor prognosis. Until now, the five-year survival rate has not been improved which brings serious challenge to human health. Lung cancer stem cells (LCSCs) serve as the root of cancer occurrence, progression, recurrence, and drug resistance. Therefore, effective anti-cancer agents and molecular mechanisms which could specifically eliminate LCSCs are urgently needed for drug design. In this article, we discovered Olig2 was overexpressed in clinical lung cancer tissues and acted as a transcription factor to regulate cancer stemness by regulating CD133 gene transcription. The results suggested Olig2 could be a promising target in anti-LCSCs therapy and new drugs targeted Olig2 may exhibit excellent clinical results. Furthermore, we verified ACT001, a guaianolide sesquiterpene lactone in phase II clinical trial with excellent glioma remission, inhibited cancer stemness by directly binding to Olig2 protein, inducing Olig2 ubiquitination degradation and inhibiting CD133 gene transcription. All these results suggested that Olig2 could be an excellent druggable target in anti-LCSCs therapy and lay a foundation for the further application of ACT001 in the treatment of lung cancer in clinical.

The S-adenosylmethionine carrier (SAMC) is a membrane transport protein located on the inner membrane of mitochondria that catalyzes the import of S-adenosylmethionine (SAM) into the mitochondrial matrix. SAMC mutations can cause a series of mitochondrial defects, including those affecting RNA stability, protein modification, mitochondrial translation and biosynthesis. Here, we describe the expression, purification and oligomerization of SAMC. The SAMC genes from three species were cloned into a eukaryotic expression vector with a GFP tag, and confocal microscopy analysis showed that these SAMCs were localized to mitochondria. A BacMam expression system was used for the expression of D. rerio SAMC with a FLAG tag. A size-exclusion chromatography analysis showed that SAMC may form a hexamer. A negative-staining electron microscopy analysis showed that SAMC formed tiny uniform particles and also confirmed the oligomerization of SAMC.

Structural and functional studies of theC-glycosyltransferase UGT708C1 provide a basis for understanding the C-glycosylation mechanism and facilitate enzyme engineering to produce bioactive C-glycosides. C-Glycosyltransferases (CGTs) catalyze the formation ofC-glycosidic bonds for the biosynthesis ofC-glycosides, but the underlying mechanism is unclear. This process improves the solubility and bioavailability of specialized metabolites, which play important roles in plant growth and development and represent rich resources for drug discovery. Here, we performed functional and structural studies of the CGT UGT708C1 from buckwheat (Fagopyrum esculentum). Enzymatic analysis showed that UGT708C1 is capable of utilizing both UDP-galactose and UDP-glucose as sugar donors. Our structural studies of UGT708C1 complexed with UDP-glucose and UDP identified the key roles of Asp382, Gln383, Thr151, and Thr150 in recognizing the sugar moiety of the donor substrate and Phe130, Tyr102, and Phe198 in binding and stabilizing the acceptor. A systematic site-directed mutagenesis study confirmed the important roles of these residues. Further structural analysis combined with molecular dynamics simulations revealed that phloretin binds to the acceptor binding pocket in a bent state with a precise spatial disposition and complementarity. These findings provide insights into a catalytic mechanism for CGTs.

Cyclocarya paliurus (Batalin) Iljinsk is a medicinal plant belonging to the Juglandaceae family, and its leaves are used for a traditional sweet herbal tea with bioactivity against obesity and hyperglycaemia in China. It contains various bioactive specialised metabolites, such as flavonoids, triterpenes and their glucosides, while no glycosyltransferases (GTs) have been reported in C. paliurus to date. Herein, we identified and cloned the first glucosyltransferase C. paliurus GT1. The expression profiles of C. paliurus GT1 showed very high expression in young leaves, callus and branches, but relatively low expression in old leaves and bark and no expression in root. The recombinant C. paliurus GT1 protein was heterologously expressed in Escherichia coli and exhibited catalytic activity towards multiple flavonoids favouring substrate- and regio-specific biosynthesis. Further enzyme assays indicated a preference for certain hydroxyl group glucosylation by C. paliurus GT1. C. paliurus GT1 actively catalysed the glucosylation of flavones and flavonols, but it was less active towards isoflavones, flavanones or triterpenes. C. paliurus GT1 was also able to catalyse the attachment of sugars to the thiol (S-) or amine (N-) sites on aromatic compounds but not on aliphatic compounds. Molecular docking and site-directed mutagenesis analyses indicated that A43F, V84P, and M201Y dramatically altered the regio-selectivity and activity, and the W283M mutation and deletion of the V309-D320 region enhanced the activity and the formation of disaccharides. Herein, we present the identification and characterization of the first multi-functional glucosyltransferase in C. paliurus and provide a basis for understanding the biosynthesis of flavonoid glucosides. C. paliurus GT1 could be utilized as a synthetic biology tool for the synthesis of O-, N-, or S-glucosylated natural/unnatural products.

Glycosyltransferases (GTs) are found in a wide variety of organisms, where they are involved in maintaining cell metabolism through glycosylation reactions. Glycosyltransferases transfer activated sugar from donor molecules to a variety of acceptors, this can alter the hydrophilic properties, stability, and chemical properties as well as subcellular location and biological activity of the acceptors. Many compounds that are modified by glycosylation are important sources of drug molecules. However, natural products contain only small amounts of glycosylated compounds, and it is very difficult to extract and purify these compounds. Furthermore, during the chemical synthesis of glycosylated compounds, the raw material reagents and generated by-products tend to cause environmental pollution, and it is not possible to achieve glycosylation at the particular acceptor sites. Recently, GTs have garnered interest among researchers. Therefore, here we review the current structural studies and biotechnological applications of plant GTs that would provide useful information for glycosylation engineering and bioactive glycoside production.

The class II hydrophobin HFBI from Trichoderma reesei was heterologously expressed by Pichia pastoris using pPIC9 vector under the control of the promoter AOX1. The recombinant HFBI (rHFBI) was purified by ultrafiltration and reverse-phase high performance liquid chromatography. Tricine-SDS-PAGE and Western blotting demonstrated that rHFBI with the expected molecular weight of 7.5 kDa was secreted into the culture medium. X-ray photoelectron spectroscopy and water contact angle measurements indicated that rHFBI could lead to the conversion of the wettability of the hydrophobic siliconized glass and hydrophilic mica surfaces relying on the self-assembly membrane on hydrophobic/hydrophilic interfaces. It was demonstrated that rHFBI had the ability to stabilize oil droplets, which was far excess of the class I hydrophobin HGFI heterologously expressed in P. pastoris (rHGFI) and the typical food emulsifier sodium caseinate. In gushing experiments, it was shown that rHFBI was a strong gushing inducer in beer, whereas rHGFI did not display any signs of gushing. This provided the potential of rHFBI to be used as a novel emulsifying agent and a predictor of gushing risk.

Human blood outgrowth endothelial cells (HBOECs)-specific binding peptide, TPSLEQRTVYAK (TPS), was proposed to be applied on autologous cell therapy for treating cardiovascular diseases. Hydrophobins, as a family of self-assembly proteins originated from fungi, have demonstrated unique characteristics to modulate surface properties of other materials coated with these amphiphilic proteins in previous studies. In this report, a fusion protein which was composed of class I hydrophobin HGFI originated from Grifola frondosa and functional peptide TPS was expressed by Pichia pastoris expression system. Then, we purified this fusion protein by ultrafiltration and reverse-phase high performance liquid chromatography. Water contact angle, X-ray photoelectron spectroscopy measurements indicated that the surface properties of hydrophobin were greatly preserved by this fusion protein while comparing with wild HGFI. Cell binding assay showed that this fusion protein demonstrated specific binding property to HBOECs while coating on biodegradable poly(ɛ-caprolactone) (PCL) grafts in the presence of fetal bovine serum, whereas HGFI-coated PCL non-selectively enhanced all types of cells attachments. Methylthiazol tetrazolium assay was employed to verify the cytocompatibility of this fusion protein-based material. This work presented a new perspective to apply hydrophobin in tissue engineering and regenerative medicine and provided an alternative approach to study endothelial progenitor cells.

The cell-specific peptide TPS (TPSLEQRTVYAK) has been proposed as a potential candidate for fabricating tissue engineering scaffolds based on its ability of binding to human endothelial progenitor cells (EPC) with high affinity and specificity. In this study, the class I hydrophobin hgfI gene from Grifola frondosa and the tps were fused and cloned into pPIC9. The fusion gene was expressed in Pichia pastoris under the control of alcohol oxidase 1 promoter. Tricine-SDS-PAGE and Western blotting confirmed that the fusion protein TPS-linker-HGFI (TLH) was successfully secreted into the culture medium. The fusion protein TLH was purified by ultrafiltration and reverse-phase high performance liquid chromatography (RP-HPLC). Water contact angle (WCA) demonstrated that similar to recombinant HGFI (rHGFI), the purified TLH could convert the surface wettability of polystyrene and mica. X-ray photoelectron spectroscopy (XPS) measurements indicated that the purified TLH could form stable films on the hydrophobic siliconized glass surface. The cell adhesion examination showed that the TLH modified poly(ε-caprolactone) (PCL) could specially facilitate the EPC (particularly EPC derived from human) binding, while rHGFI modified PCL could nonselectively enhance cells adhesion. To the best of our knowledge, this is the first report that demonstrates that the TPS peptide was immobilized on biomaterial-PCL surface by fusion with hydrophobin. The potential application of this finding in combination with biomedical devices for EPC culture, will facilitate the current techniques used for cell-based therapies.

Hydrophobins are small secreted proteins produced by filamentous fungi,which can form an amphipathic membrane at various surfaces.Hydrophobins have been considered as excellent substrates for protein immobilization.However,the driven force for protein adsorption on hydrophobin surface is not clear.In this work,we systematically investigated the protein adsorption on hydrophobins at different pH and ionic strength.Firstly,the adsorption of class Ⅰ hydrophobin HGFI and class Ⅱ hydrophobin HFBI on the surfaces of polystyrene were investigated via quartz crystal microbalance with dissipation monitoring(QCM-D) at different pH and ionic strength.The results show that both pH and ionic strength have greater impacts on the adsorption of HGFI on polystyrene than that of HFBI.Moreover,HGFI can form soft films on the polystyrene,whereas HFBI formed very rigid films under the same conditions.The adsorption of BSA and avidin on the HGFI and HFBI were further investigated by using QCM-D at the same pH and ionic strength.The results indicate that adsorptions of BSA and avidin on the HGFI and HFBI are dramatically affected by both pH and ionic strength,suggesting that the major driving force dominating the protein adsorption on hydrophobin is the electrostatic force.This study provides a theoretical guide for a controllable immobilization of a protein on a hydrophobin surface.