Controlled Reversible N-Terminal Modification of Peptides and Proteins.

A reversible modification strategy enables a switchable cage/decage process of proteins with an array of applications for protein function research. However, general N-terminal selective reversible modification strategies which present site selectivity are specifically limited. Herein, we report a general reversible modification strategy compatible with 20 canonical amino acids at the N-terminal site by the palladium-catalyzed cinnamylation of native peptides and proteins under biologically relevant conditions. This approach broadens the substrate adaptability of N-terminal modification of proteins and shows a potential impact on the more challenging protein substrates such as antibodies. In the presence of 1,3-dimethylbarbituric acid, palladium-catalyzed deconjugation released native peptides and proteins efficiently. Harnessing the reversible nature of this protocol, practical applications were demonstrated by precise function modulation of antibodies and traceless enrichment of the protein-of-interest for proteomics analysis. This novel on/off strategy working on the N-terminus will provide new opportunities in chemical biology and medicinal research.

Site- and Stereoselective Glycomodification of Biomolecules through Carbohydrate-Promoted Pictet-Spengler Reaction.

Carbohydrates play pivotal roles in an array of essential biological processes and are consequently involved in many diseases. To meet the needs of glycobiology research, chemical enzymatic and non-enzymatic methods have been developed to generate glycoconjugates with well-defined structures. Herein, harnessing the unique properties of C6-oxidized glycans, we report a straightforward and robust strategy for site- and stereoselective glycomodification of biomolecules with N-terminal tryptophan residues by a carbohydrate-promoted Pictet-Spengler reaction, which is not adapted to typical aldehyde substrates under biocompatible conditions. This method reliably delivers highly homogeneous glycoconjugates with stable linkages and thus has great potential for functional modulation of peptides and proteins in glycobiology research. Moreover, this reaction can be performed at the glycosites of glycopeptides, glycoproteins and living-cell surfaces in a site-specific manner. Control experiments indicated that the protected α-O atom of aldehyde donors and free N-H bond of the tryptamine motif are crucial for this reaction. Mechanistic investigations demonstrated that the reaction exhibited a first-order dependence on both tryptophan and glycan, and deprotonation/rearomatization of the pentahydro-ß-carbolinium ion intermediate might be the rate-determining step.

Enhanced antibody-defucosylation capability of α-L-fucosidase by proximity-based protein fusion.

Up to date, the reported fucosidases generally show poor activities toward the IgG core-fucose, which limits the efficiency of ENGase-catalyzed glycoengineering process. However, EndoS or EndoS2 owns excellent activity and great selectivity towards the N-glycosylation of IgGs, and their non-catalytic domains are deduced to have specific interactions to IgG Fc domain that result in the great activity and selectivity. Herein, we constructed a series fusion protein of AlfC (an α-l-fucosidase from Lactobacillus casei BL23) with EndoS/S2 non-catalytic domain by replacing the catalytic GH (glycan hydrolase) domain of EndoS/S2 with the AlfC. We found that all these fused AlfCs showed significantly enhanced defucosylation activity toward the deglycosylated IgGs (Fucα1,6GlcNAc-IgG). We also performed the kinetic study of these fusion enzymes, and our results tend to tell that the EndoS-based fusion proteins have higher kcat values while the EndoS2-based ones possess lower Km values other than higher kcat. Conclusively, our research provides an effective approach to improve the activity of AlfC and remarkably shortened the defucosylation process within several minutes, which will significantly promote the development of glycoengineered antibodies in the future.

Correction: Enhanced transglycosylation activity of an Endo-F3 mutant by ligand-directed localization.

Correction for 'Enhanced transglycosylation activity of an Endo-F3 mutant by ligand-directed localization' by Xiangman Zou et al., Org. Biomol. Chem., 2022, 20, 3086-3095, https://doi.org/10.1039/D2OB00030J.

Enhanced transglycosylation activity of an Endo-F3 mutant by ligand-directed localization.

At present, numerous studies have been reported to remodel the N-glycans of therapeutic antibodies for the gain of functions. Among the ways of remodeling antibody N-glycans, the chemoenzymatic glycoengineering approach by endoglycosidase (ENGase) has been deeply investigated and provided a significant tool for IgG glycoengineering. Among these cases, the transglycosylation activity of Endo-F3, compared to Endo-S and S2, is insufficient and limits its power in remodeling IgG glycosylation. Herein, we chemically conjugated the Endo-F3 mutant D165A with an Fc binding peptide (FcBP), aiming to improve the affinity of Endo-F3 D165A to IgGs, and therefore enhance the transglycosylation activity of D165A. In this report, we investigated the conjugation site of FcBP to D165A and the linkers between them and found that the conjugation indeed significantly increases the transglycosylation activity of D165A. Meanwhile, we optimized the FcBP-D165A catalyzed transglycosylation process, including the enzyme quantity, oxazoline concentration, and so on. Finally, by this method, we remodeled the N-glycans of rituximab and trastuzumab into homogeneous S2G2F, G2F, GN2M3, and M3 types with decreased enzyme quantity, oxazoline ratio, and catalyzing time. This method not only provides an enhanced ENGase for IgG glycoengineering but also suggests that ligand-directed localization of enzymes is a potential strategy to enhance the activity of enzymes towards the targeted substrate.

Design, synthesis, and antibacterial evaluation of vancomycin-LPS binding peptide conjugates.

Developing novel antibiotics is urgently needed with emergency of drug resistance. Vancomycin, the last resort for intractable Gram-positive bacterial infections, is ineffective against Gram-negative bacteria and vancomycin resistant bacteria. Herein, we report a series of novel vancomycin derivatives carrying LPS binding peptides, vancomycin-LPS binding peptide conjugates (VPCs). The LPS binding peptides were conjugated onto 4 sites of vancomycin via CuAAC or maleimide- sulfydryl addition, and the formed VPCs were screened against VISA/VRE and Gram-negative strains. VPCs exhibited enhanced activity against vancomycin resistant bacteria and obtained the activity against Gram-negative bacteria in vitro, providing a novel strategy for vancomycin modification and glycopeptide antibiotics synthesis.

A facile method for vancomycin C-terminus functionalization and derivatization through hydrazide.

Over 60-year clinical use of vancomycin led to the emergence of vancomycin-resistant bacteria and threatened our health. To combat vancomycin-resistant strains, numerous vancomycin analogues were developed, such as Telavancin, Oritavancin and Dalbavancin. Extra structures embedded on C-terminus has been proved to be an effective strategy to promote antibacterial activity of vancomycin against vancomycin-resistant strains. Here, we reported a facile strategy, inspired by native chemical ligation, for vancomycin C-terminus functionalization and derivatization. The introduction of C-terminal hydrazide on vancomycin not only provided us an accessible method for C-terminus functionalization through carbonyl azide and thioester, also acted as an efficient site for vancomycin structure modifications. Based on hydrazide-vancomycin, we effectively conjugated cysteine and cysteine containing peptides onto vancomycin C-terminus, and two fluorescent FITC-vancomycin were prepared through Cys-Maleimide conjugation. Meanwhile, we introduced lipophilic structures onto vancomycin C-terminus via the hydrazide moiety. The obtained vancomycin derivatives were evaluated against both Gram-positive and negative bacteria strains.

Recent advances in antibody glycoengineering for the gain of functions.

Glycans play important roles in antibody functions, and antibody glycoengineering has long been an important research field. Here, we summarize the significant strategies of antibody glycoengineering, including expressed antibody glycoengineering in mammalian cell expression systems, chemo-enzymatic antibody glycoengineering, and yeast expression system-based antibody engineering, as well as the applications of glycoengineering in antibody-drug conjugates. These advances in antibody glycoengineering will provide a comprehensive understanding and inspire us to develop more advanced techniques to achieve glycoengineered antibodies.

Advances in MiRNAs Involved in Endometrial Carcinoma.

Endometrial carcinoma (EC) is a common malignancy worldwide. Existing evidence has revealed that EC could be associated with abnormal gene expression. Meantime, evidence supports that miRNAs act as critical regulators in gene expression through the binding to the 3'- untranslated region (3'-UTR). Accordingly, this review concludes some recent studies focusing on miRNAs that influence EC, aiming at understanding the association between miRNAs and EC more clearly and providing a reference for further studies on miRNA-related drugs treating EC.

Association of the PROGINS PgR polymorphism with susceptibility to female reproductive cancer: A meta-analysis of 30 studies.

AIMS: The progesterone response of the nuclear progesterone receptor plays an important role in the female reproductive system. Changes in the function of the progesterone receptor gene may increase the risk of reproductive cancer. The present study performed a meta-analysis to examine whether the progesterone receptor gene PROGINS polymorphism was a susceptibility factor for female reproductive cancer. MATERIALS AND METHODS: We searched the PubMed, Cochrane Library, Web of Science and EMBASE databases for literature on PROGINS polymorphisms and female reproductive cancer published before September 2020. We evaluated the risk using odds ratios [ORs] and 95% confidence intervals via fixed effects models and random-effects models, which were calculated for all five genetic models. We grouped the analyses by race, cancer, and HWE. RESULTS: Thirty studies comprised of 25405 controls and 19253 female reproductive cancer cases were included in this meta-analysis. We observed that the Alu insertion polymorphism and the V660L polymorphism were significantly associated with female reproductive cancer in the allele and dominant genetic models. The allele genetic model and (Alu-insertion polymorphism: OR = 1.22, 95% CI = 1.02-1.45; V660L polymorphism: OR = 1.02, 95% CI = 1.00-1.13) dominant genetic model (Alu-insertion polymorphism: OR = 1.27, 95% CI = 1.03-1.58; V660L polymorphism: OR = 1.10, 95% CI = 1.011.19) demonstrated a significantly increased risk of female reproductive cancer. A subgroup analysis according to ethnicity found that the Alu insertion was associated with female reproductive cancer incidence in white (Allele model: OR = 1.21, 95% CI = 1.00-1.45; Heterozygous model: OR = 3.44, 95% CI = 1.30-9.09) and Asian (Dominant model: OR = 3.12, 95% CI = 1.25-7.79) populations, but the association disappeared for African and mixed racial groups. However, the V660L polymorphism was significantly associated with female reproductive cancer in the African (Allele model: OR = 2.52, 95% CI = 1.14-5.56; Heterozygous model: OR = 2.83, 95% CI = 1.26-6.35) and mixed racial groups (Dominant model: OR = 1.28, 95% CI = 1.01-1.62). Subgroup analysis by cancer showed that the PROGINS polymorphism increased the risk of cancer in the allele model, dominant mode and heterozygous model, but the confidence interval for this result spanned 1 and was not statistically significant. This sensitivity was verified in studies with HWE greater than 0.5. CONCLUSION: Our meta-analysis showed that the progesterone receptor gene Alu insertion and the V660L polymorphism contained in the PROGINS polymorphism were susceptibility factors for female reproductive cancer.

A novel genotyping technique for discriminating LVAS-associated high-frequency variants in SLC26A4 gene.

An increasing number of biological and epidemiological evidence suggests that c.919-2A > G and c.2168A > G variants of solute carrier family 26, member 4 (SLC26A4) gene play a critical role in the development of large vestibular aqueduct syndrome (LVAS). In this study, we developed a rapid genotyping method for discriminating LVAS-associated high-frequency variants in SLC26A4 gene. The genotyping technique consists of 3' terminal exonuclease-resistant phosphorothioate-modified allele specific primer extension mediated by exo+ polymerase. In PCR amplification by Pfu polymerase, allelic specific primers perfectly matching wild type allele were extended while no specific products were yielded from primers targeting variant allele. Similarly, allelic specific primers perfectly matching variant allele were extended and no specific products were observed from primers targeting wild type allele. The clinical application of 3' terminal phosphorothioate-modified allele specific primer extension mediated by Pfu polymerase identified both homozygous for SLC26A4 gene c.919-2A > G variant in two patients clinically diagnosed as LVAS by temporal bone CT scan. The genetic results from this method are consistent with that of DNA sequencing. The data suggest that exo+ polymerase-mediated 3' terminal phosphorothioate-modified primer extension is reliable in the identification of SLC26A4 gene high-frequency variant prior to high-resolution CT scan. The method is extremely suitable for quickly molecular etiologic screening and early diagnosis and aggressive prevention therapy of LVAS.