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Cobalamin-dependent radical S-adenosyl-L-methionine protein functions with a partner to successively methylate tricyclic indole alkaloid for chuangxinmycin maturation and derivatization

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Science China Chemistry 2025年第01期 308-316页

作者： Sili Wang Jiancheng Huang Yanan Du Wei Huang Yufeng Xue Xiaokun Xu Guannan Zhong Yuanyuan Shi Bin Hong Xiaoying Bian Wen Liu State Key Laboratory of chemical biology Shanghai Institute of Organic Chemistry University of Chinese Academy of SciencesChinese Academy of Sciences State Key Laboratory of Microbial Technology Shandong University National Health Commission (NHC) Key Laboratory of biotechnology for Microbial Drugs Institute of Medicinal BiotechnologyChinese Academy of Medical Science & Peking Union Medical College

Cobalamin(Cbl)-dependent radical S-adenosyl-L-methionine(SAM) proteins constitute the largest collection of the radical SAM superfamily that has hundreds of thousands of individual members. Many of these proteins are involved in the biosynthesis of pharmaceutically important natural products to catalyze chemically demanding reactions. In the biosynthetic pathway of chuangxinmycin(CXM), a unique indole alkaloid antibiotic with potent anti-infective activity, functionalization of the characteristic thiopyrano[4,3,2-cd]indole scaffold by regio-and stereoselective C3-methylation is believed to rely on a Cbl-dependent radical process, which, however, remained to be reconstituted biochemically. We here report the dissection of this enzymatic process, which requires the incorporation of Cxm8, a Cbl-dependent radical SAM protein, with Cxm9, a DUF5825family protein that shares no homology to any proteins of known functions. Cxm8 and Cxm9 function together by forming an unexpected heterodimeric complex that selectively catalyzes C3-methylation of the tricyclic indole-S-hetero ring system in a successive manner, achieving CXM and a recently identified, C3-dimethylated congener. Detailed biochemical characterization,isotope labeling, structural simulation and bioinformatics analysis rationalized the catalysis of the Cxm8/Cxm9 complex and particularly the necessity of the DUF5825 protein for C3-methylase activity. This is the first example that a Cbl-dependent protein acts with a partner to exhibit radical SAM activity.

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chemical stability of doped BaCeO_3-BaZrO_3 solid solutions in different atmospheres

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Journal of Rare Earths 2008年第4期26卷 505-510页

作者：吕敬德王岭樊丽华李跃华戴磊郭红霞 college of chemical Engineering and biotechnology Hebei Polytechnic University

BaCe0.45Zr0.45M0.1O3-δ （M=Y, In） and BaCe0.9Y0.1O3-δ were prepared through the conventional solid state reaction route. The chemical stability was investigated in hydrogen, carbon dioxide, and boiling water. Crystalline phase and microsa-ucture of the proton conductor before and after stability test were measured with X-ray diffraction （XRD） and scanning electron microscopy （SEM）, respectively. The results showed that all materials were quite stable in H2 atmosphere. In CO2 atmosphere, BaCe0.45Zr0.45M0.1O3-δ（M=Y, In） were relatively stable, while Bafe0.9Y0.1O3-δ decomposed. In boiling water, BaCe0.9Y0.1O3-δ was quickly decomposed into Ba（OH）2 and corresponding oxide. BaCe0.45Zr0.45M0.1O3-δ slightly reacted with boiling water and some amorphous phases were formed. However, BaCe0.45Zr0.45In0.1O3-δ was observed to exhibit better stability than BaCe0.45Zr0.45Y0.1O3-δ in water. The experimental results were interpreted in terms of thermodynamic data and tolerance factor.

关键词： BaCeO3 BaZrO3 proton conductor chemical stability different atmospheres rare earths

Formation of multifunctional Fe_3O_4/Au composite nanoparticles for dual-mode MR/CT imaging applications

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Chinese Physics B 2014年第7期23卷 22-29页

作者：胡勇李静超沈明武史向阳 college of Chemistry Chemical Engineering and BiotechnologyDonghua University

Recent advances with iron oxide/gold （Fe3O4/Au） composite nanoparticles （CNPs） in dual-modality magnetic reso- nance （MR） and computed tomography （CT） imaging applications are reviewed. The synthesis and assembly of＂dumbbell- like＂ and ＂core/shell＂ FeaO4/Au CNPs is introduced. Potential applications of some developed Fe3O4/Au CNPs as contrast agents for dual-mode MR/CT imaging applications are described in detail.

关键词： iron oxide nanoparticles gold nanoparticles magnetic resonance imaging computed tomographyimaging

Genes and proteins expressed at different life cycle stages in the model protist Euplotes vannus revealed by both transcriptomic and proteomic approaches

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Science China Life Sciences 2025年第01期 232-248页

作者： Yaohan Jiang Xiao Chen Chundi Wang Liping Lyu Saleh A.Al-Farraj Naomi A.Stover Feng Gao Key Laboratory of Evolution & Marine Biodiversity (Ministry of Education) and Institute of Evolution & Marine Biodiversity Ocean University of China Marine college Shandong University Zoology Department College of ScienceKing Saud University Department of biology Bradley University Laboratory for Marine biology and biotechnology Qingdao Marine Science and Technology Center

Sexual reproduction first appeared in unicellular protists and has continued to be an essential biological process in almost all *** protists, which contain both germline and somatic genomes within a single cell, have evolved a special form of sexual reproduction called conjugation that involves mitosis, meiosis, fertilization, nuclear differentiation, genome rearrangement, and the development of unique cellular structures. The molecular basis and mechanisms of conjugation vary dramatically among ciliates, and many details of the process and its regulation are still largely unknown. In order to better comprehend these processes and mechanisms from an evolutionary perspective, this study provides the first comprehensive overview of the transcriptome and proteome profiles during the entire life cycle of the newly-established marine model ciliate Euplotes vannus. Transcriptome analyses from 14 life cycle stages(three vegetative stages and 11 sexual stages) revealed over 26,000 genes that are specifically expressed at different stages, many of which are related to DNA replication,transcription, translation, mitosis, meiosis, nuclear differentiation, and/or genome rearrangement. Quantitative proteomic analyses identified 338 proteins with homologs associated with conjugation and/or somatic nuclear development in other ciliates, including dicer-like proteins, Hsp90 proteins, RNA polymerase Ⅱ and transcription elongation factors, ribosomal-associated proteins, and ubiquitin-related proteins. Four of these homologs belong to the PIWI family, each with different expression patterns identified and confirmed by RT-qPCR,which may function in small RNA-mediated genome rearrangement. Proteins involved in the nonhomologous end-joining pathway are induced early during meiosis and accumulate in the developing new somatic nucleus, where more than 80% of the germline sequences are eliminated from the somatic genome. A number of new candidate genes and proteins likely t

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N-cap helix nucleation： methods and their applications

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Science China Chemistry 2017年第6期60卷 689-700页

作者： Dongyuan Wang Xuan Qin Hui Zhao Zigang Li School of chemical biology and biotechnology Shenzhen Graduate School of Peking University Shenzhen 518055 China

Recapitulation of well-defined α-helices could result in constrained peptide mimetics with preferable secondary structures and enhanced therapeutic properties for various purposes. Among the helix-stabilizing strategies, the nucleation strategies are able to maximize recognition specificity of the original sequence without compromising the molecular recognition surface. In this review,current methodologies of helix nucleation are introduced including their constructing strategies, structure features and proof of concept biological applications.

关键词： α-helices helix nucleation constrained strategies biological applications

Synthesis and electrochemical properties of a chiral silyl-substituted tetrathiafulvalene derivative

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Chinese chemical Letters 2014年第4期25卷 579-582页

作者： Guo-Qi Liang Zhong-Bao Zhang Hong-Qi Li Ya-Ping Wang Chun-Ying Xian college of Chemistry Chemical Engineering and BiotechnologyDonghua University

A new chiral tetrathiafulvalene （TTF） derivative and related silyl-substituted 1,3-dithiole-2-（thi）one compounds were synthesized and characterized by 1H NMR, 13C NMR, MS and IR spectra. Single crystal structure of the silyl-substituted 1,3-dithiole-2-one revealed the high degree of conjugation of the five- membered ring moiety in the compound. The electrochemical properties of the new TTF derivative were studied by cyclic voltammetry and the results indicated that the electron-donating ability of the chiral TI＂F derivative was similar to that of BEDT-TTF. The AE value for the new TTF derivative was smaller than those for TTF and BEDT-TrF, indicative of decreased Coulombic repulsion in the dicationic redox state. Formation of charge-transfer （CT） complex between the new donor and electron acceptor 2,3-dichloro-5,6-dicvano-1,4-benzocluinone （DDO） was demonstrated.

关键词： Tetrathiafulvalene Chiral Silyl Electrochemistry

Effect of the position of substitution on the electronic properties of nitrophenyl derivatives of fulleropyrrolidines:Fundamental understanding toward raising LUMO energy of fullerene electron-acceptor

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Chinese chemical Letters 2014年第4期25卷 501-504页

作者： Xuan Zhang Xu-Dong Li college of Chemistry Chemical Engineering & BiotechnologyDonghua University

A series of substituted para-, meta- and ortho-nitrophenyl derivatives of fulleropyrrolidine were synthesized to investigate the effects of the position of substitution on electronic properties by using steady-state absorption and fluorescence spectra, combined with DFT calculations. The results confirmed that the position of substitution has little effect on absorption and fluorescence spectra, whereas a significant effect was observed on their LUMO energy levels. The theoretical calculations revealed that the LUMO energy of the ortho-nitrophenyl substituted derivative was increased 0.1 eV above those ofpara- and meta-substitution. The prominent effect ofortho-substitution was attributed to the through-space orbital interaction between spatially closed electron-withdrawing nitro group and fullerene cage. These findings could provide fundamental insights in raising LUMO levels of C6o-based electron acceptor materials and an alternative strategy to increase open circuit voltage Voc in polymer solar cells.

关键词： Fullerene Substituent effect Orbital interaction Organic photovoltaics

Solvent atmosphere controlled self-assembly of unmodified C_(60):A facile approach for constructing various architectures

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Chinese chemical Letters 2014年第6期25卷 912-914页

作者： Xuan Zhang Xu-Dong Li college of Chemistry Chemical Engineering & BiotechnologyDonghua University

A facile approach for constructing diverse architectures of unmodified C60 was developed via simple evaporation of pure C60 solution in CS2 under various poor solvent atmospheres. Diverse architectures such as belts, sheets, and starfishes were successfully constructed under different experimental conditions. C60 belts obtained under EtOH atmosphere were confirmed to be a face-centered cubic （fcc） structure. The solvent atmospheres not only slowed clown the evaporation speed, but also could reorganize the self-assembly of C60 by partially re-dissolving the initially formed architectures. This concept represents a novel method for preparation of nanostructures of C60 and could also be applied for controlling of the self-assembly of other functional organic molecules.

关键词： Fullerene Self-assembly Nanostructure Atmosphere Evaporation

Semi-synthesis of disulfide-linked branched tri-ubiquitin mimics

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Science China Chemistry 2018年第4期61卷 412-417页

作者： Yanyan Si Lujun Liang Shan Tang Yunkun Qi Yong Huang Lei Liu Key Laboratory of chemical Genomics School of Chemical Biology and BiotechnologyPeking UniversityShenzhen Graduate School Department of Chemistry Tsinghua University

Ubiquitin(Ub) chain isopeptide bond mimics are useful molecules for biochemical and biophysical studies. Herein, we report the semi-synthesis of the disulfide-linked K11/K48-branched tri-Ub(Ub_3^(11/48)(S-S)), the first example of an isopeptide mimic for the branched Ub chains,which have recently emerged as an interesting category of Ub modifications. Our strategy comprised the El-dependent synthesis of the Ub conjugate of aminoethanethiol, followed by disulfide formation with Ub(K11 C, K48 C). The structure of the synthetic isopeptide bond mimics was verified by the crystal structure of Ub_3^(11/48)(S-S). Deubiquitination and pulldown assays indicated that the synthetic Ub_3^(11/48)(S-S) could be hydrolyzed by linkage-specific deubiquitinases(K11-specific Cezanne and K48-specific OTUB1), and recognized by proteasomal ubiquitin receptor S5 a.

关键词： ubiquitin chain isopeptide bond mimics disulfide-directed strategy branched Ub chains crystal structure