production-sars-cov-2-virus-like-particle-system-to-investigate-viral

Production of a SARS-CoV-2 Virus-Like-Particle System to Investigate Viral Life Cycles <em>In Vitro</em>

The severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) virus-like particle (SC2-VLP) method offers a powerful and accessible tool for studying ...

structural-biology-analytical-chemistry-approaches-for-characterizing

Structural Biology and Analytical Chemistry Approaches for Characterizing <em>C</em>-Glycoside Metabolic Enzymes in Human Gut Microbiota

The gut microbiota has emerged as a key modulator of host health, particularly because of its capacity to metabolize dietary glycosides. While ...

Beijing University of Chinese Medicine

Glycosidic bond of C-glycosides is difficult to be broken due to its chemical stability. Screening specific microbe from microbiota is a practical way to deglycosylate these compounds. In this study, a new strain W974-1 which is capable of cleaving C-glycosidic bonds was isolated from human gut microbiota by spread plate method. It deglycosylates flavonoid 8-C-glycosides such as orientin and vitexin to their aglycones with the enzymes secreted outside the bacterial cells. This strain was identified as Enterococcus avium by 16S rDNA sequencing, physiological and biochemical characterization.

A newly isolated human intestinal strain deglycosylating flavonoid C-glycosides.

The -glycosidic bond that connects the sugar moiety with aglycone is difficult to be broken or made due to its inert nature. The knowledge of -glycoside breakdown and synthesis is very limited. Recently, the enzyme DgpA/B/C cascade from a human intestinal bacterium PUE was identified to specifically cleave the -glycosidic bond of puerarin (daidzein-8--glucoside). Here we investigated how puerarin is recognized and oxidized by DgpA based on crystal structures of DgpA with or without substrate and biochemical characterization. More strikingly, we found that apart from being a -glycoside cleaving enzyme, DgpA/B/C is capable of efficiently converting - to -glycoside showing the activity as a structure isomerase. A possible mechanistic model was proposed dependently of the simulated complex structure of DgpB/C with 3″-oxo-daidzin and structure-based mutagenesis. Our findings not only shed light on understanding the enzyme-mediated -glycosidic bond breakage and formation, but also may help to facilitate stereospecific -glycoside synthesis in pharmaceutical industry.

Structural mechanism of a dual-functional enzyme DgpA/B/C as both a -glycoside cleaving enzyme and an - to -glycoside isomerase.

 an insufficient coat protein complex I (COPI) retrieval signal, the majority of SARS-CoV-2 spike (S) is resident in host early secretory organelles and a tiny amount is leaked out in cell surface. Only surface-exposed S can be recognized by B cell receptor (BCR) or anti-S therapeutic monoclonal antibodies (mAbs) that is the trigger step for B cell activation after S mRNA vaccination or infected cell clearance by S mAbs. Now, a drug strategy to promote S host surface exposure is absent. Here, we first combined structural and biochemical analysis to characterize S COPI sorting signals. A potent S COPI sorting inhibitor was then invented, evidently capable of promoting S surface exposure and facilitating infected cell clearance by S antibody-dependent cellular cytotoxicity (ADCC). Importantly, with the inhibitor as a probe, we revealed Omicron BA.1 S is less cell surface exposed than prototypes because of a constellation of S folding mutations, possibly corresponding to its ER chaperone association. Our findings not only suggest COPI is a druggable target against COVID-19, but also highlight SARS-CoV-2 evolution mechanism driven by S folding and trafficking mutations.

SARS-CoV-2 spike host cell surface exposure promoted by a COPI sorting inhibitor.

Triptolide is a predominant active component of Triptergium wilfordii Hook. F, which has been used for the treatment of cancers and autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus and diabetic nephropathy. Therefore, triptolide and its derivates are considered to have promising prospects for development into drugs. However, the clinical application of triptolide is limited due to various organ toxicities, especially liver toxicity. The potential mechanism of triptolide-induced hepatotoxicity has attracted increasing attention. Over the past five years, studies have revealed that triptolide-induced liver toxicity is involved in metabolic imbalance, oxidative stress, inflammations, autophagy, apoptosis, and the regulation of cytochrome P450 (CYP450) enzymes, gut microbiota and immune cells. In this review, we summarize the pharmacological applications and hepatotoxicity mechanism of triptolide, which will provide solid theoretical evidence for further research of triptolide.

Recent advances in the pharmacological applications and liver toxicity of triptolide.

Optimize the extraction process of earthworm fibrinolytic enzyme.

Optimization of High-Activity earthworm fibrinolytic enzyme extraction methods and protein component analysis.

The Cyclic GMP-AMP synthase (cGAS) and cGAS/DncV-like nucleotidyltransferase (CD-NTase) enzymes belong to the key components of the innate immune sensor system that generates cyclic dinucleotide molecules in response to danger signals. Recently, it was discovered that CD-NTase in bacteria can undergo conjugation to protein substrates via an E1/E2 enzyme-mediated process, resembling ubiquitin modification system. Subsequently, these CD-NTase conjugated molecules will be hydrolyzed by the Cap3 enzyme in the same gene cluster. However, the experimental structure of bacterial CD-NTase recognized by Cap3 is unknown. Here, we first determined the crystal structure of the Cap3 enzyme in complex with the C-terminal tail of CD-NTase. Our structural and enzymatic analysis revealed that the C-terminal tail of CD-NTase is both necessary and sufficient for the Cap3-mediated hydrolysis of CD-NTase from its substrates. Interestingly, we further observed that after the hydrolysis reaction, the terminal glycine residue of the CD-NTase C-terminal tail was sequentially removed by Cap3, indicating that Cap3 might play a role in quenching the CD-NTase conjugation reaction. Our work provides experimental evidence elucidating the interaction between Cap3 and CD-NTase, and suggests a potential role for Cap3 in the bacterial Cyclic-oligonucleotide-based anti-phage signaling system (CBASS).

Structural and functional characterization of the bacterial Cap3 enzyme in deconjugation and regulation of the cyclic dinucleotide transferase CD-NTase.

ArticleTotal : 2	Year
Publication title	2025
Publication title	2025

Article	Year
A newly isolated human intestinal strain deglycosylating flavonoid C-glycosides. Archives of microbiology\| PubMed ID: 35536516	2022
Structural mechanism of a dual-functional enzyme DgpA/B/C as both a -glycoside cleaving enzyme and an - to -glycoside isomerase. Acta pharmaceutica Sinica. B\| PubMed ID: 36815035	2023
SARS-CoV-2 spike host cell surface exposure promoted by a COPI sorting inhibitor. Acta pharmaceutica Sinica. B\| PubMed ID: 37360012	2023
Recent advances in the pharmacological applications and liver toxicity of triptolide. Chemico-biological interactions\| PubMed ID: 37516378	2023
Optimization of High-Activity earthworm fibrinolytic enzyme extraction methods and protein component analysis. Journal of chromatography. B, Analytical technologies in the biomedical and life sciences\| PubMed ID: 38878711	2024
Structural and functional characterization of the bacterial Cap3 enzyme in deconjugation and regulation of the cyclic dinucleotide transferase CD-NTase. Biochemical and biophysical research communications\| PubMed ID: 38968768	2024

Wenfu MA

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