检索结果-南通市图书馆

同方期刊数据库

Screening and identification of receptor antagonist for shiga toxin from random peptides displayed on filamentous bacteriophages

在线全文

学校读者我要写书评

暂无评论

Science China(Life Sciences) 1999年第1期42卷 43-49页

作者：韩照中苏国富黄翠芬 1. institute of biotechnology 100071 Beijing China

The bacteriophage clones which can bind with shiga toxin B subunit (StxB) and inhibit cytotoxicity of shiga toxin were obtained by using antibody capturing method from a 1.-mer random peptide library displayed on the surface of bacteriophage fd. Among them, one peptide encoded by the random DNA region of a selected bacteriophage (A1.) was synthesized and tested in vitro and in vivo, where the peptide competed with the receptor of shiga toxin to bind StxB, and inhibited the cytotoxicity and enterotoxicity of shiga toxin. The peptide can also block other apparently unrelated StxB binding bacteriophage (A3), which suggests that there are overlapping StxB interaction sites for those ligands with different sequences. The results provide a demonstration of bacteriophage display to screen peptide ligands for a small and/or unable biotinylated molecule by antibodies-capturing strategy, and take the lead for the development of receptor antagonists for shiga toxin.

关键词： bacteriophage display peptide library shiga toxin receptor antagonist.

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

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2025年第1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.

关键词：

同方期刊数据库

Construction of a trivalent candidate vaccine against Shigella species with DNA recombination

在线全文

学校读者我要写书评

暂无评论

Science China(Life Sciences) 2002年第1期45卷 10-20页

作者：王恒樑廖翔苏国富冯尔玲金明黄翠芬林云黄留玉 1. Beijing institute of {1. 100071 Beijing China

In this work asd gene of Shigella flexneri 2a strain T32 was replaced by Vibrio cholerae toxin B subunit (ctxB) gene with DNA recombination in vivo and in vitro. The resulting derivative of T32, designed as FWL01. could stably express CtxB, but its growth in LB medium depended on the presence of diaminopimelic acid (DAP). Then form I plasmid of Shigella sonnei strain S7 was labeled with strain T32 asd gene and mobilized into FWL01. Thus a trivalent candidate oral vaccine strain, designed as FSW01. was constructed. In this candidate strain, a balanced-lethal system was constituted between the host strain and the form I plasmid expressing S. sonnei O antigen. Therefore the candidate strain can express stably not only its own O antigen but also CtxB and O antigen of S. sonnei in the absence of any antibiotic. Experiments showed that FSW01.did not invade HeLa cells or cause keratoconjunctivitis in guinea pigs. However, rabbits immunized FSW01.can elicit significant immune responses. In mice and rhesus monkey models, vaccinated animals were protected against the challenges of wild S. flexneri 2a strain 2457T and S. sonnei strain S9.

关键词： Shigella spp., ctxB gene, balanced-lethal system, vaccine.

Complete nucleotide sequence and genome organization of tobacco mosaic virus isolated from Viciafaba

在线全文

学校读者我要写书评

暂无评论

Science China(Life Sciences) 2000年第2期43卷 200-208页

作者：周雪平薛朝阳陈青戚益军李德葆 1. institute of biotechnology Zhejiang University (Huajiachi) 310029 Hangzhou China

Based on reported TMV-U1.sequence, primers were designed and fragments covering the entire genome of TMV broad bean strain (TMV-B) were obtained with RT-PCR. These fragments were cloned and sequenced and the 5’ and 3’ end sequences of genome were confirmed with RACE. The complete sequence of TMV-B comprises 6 395 nucleotides (nt) and four open reading frames, which correspond to 1.6 ku (1.1.6 amino acids), 1.3 ku (1.61. amino acids), 30 ku (268 amino acids) and 1..5 ku proteins (1.9 amino acids). The complete nucleotide sequence of TMV-B is 99.4% identical to that of TMV-U1. The two virus isolates share the same sequence of 5’, 3’ non-coding region and 1..5 K ORF, and 6, 1.and 3 amino acid changes are found in 1.6 K protein, 54 K protein and 30 K protein, respectively. The possible mechanism on the infection of TMV-B in Vicia faba is discussed.

关键词： tobacco mosaic virus Vicia faba complete nucleotide sequence.

CS3 fimbriae of enterotoxigenic Escherichia coli as chimeric expression carriers of heterologous antigenic determinants

在线全文

学校读者我要写书评

暂无评论

Science China(Life Sciences) 1999年第2期42卷 128-135页

作者：董自正张兆山李淑琴张蓓宁黄翠芬 1. Laboratory of Gene Engineering Institute of Biotechnology 100071 Beijing China

CS3 fimbriae, which are the strong immunogen, are produced by human enterotoxigenic Escherichia coli (ETEC). The possibility of using CS3 as a carrier of foreign antigenic determinants was investigated. A SacⅡ site sequence was inserted into the structural gene of CS3 subunit by site-specific mutagenesis based on analyzing and predicting the properties of the proteins. A recombinant strain expressing CS3/CTP3 hybrid fimbriae was constructed by inserting the sequence encoding CTP3 into the SacII site created by directed mutagenesis in the structural gene of CS3 subunit and transforming the recombinant plasmid into the host of DH5α. The result of SDS-PAGE showed that the hybrid CS3/CTP3 molecules were the fusion proteins with molecular masses of about 1..5 ku. Inoculating mice orally and intraperitoneally showed that both antibodies against CS3 and CTP3 were elicited. These results indicate that CS3 pili could be an exposure vector for heterologous antigenic determinants and become a powerful tool for the development of oral vaccines directed against mucosal pathogens.

关键词： CS3 fimbriae gene fusion chimeric proteins expression carrier.

Establishment of Smad2 conditional gene targeting mice based on the Cre-LoxP system

在线全文

学校读者我要写书评

暂无评论

Science China(Life Sciences) 2002年第2期45卷 129-137页

作者：周江黄培堂程萱黄翠芬孙彦洵杨晓 1. Genetic Laboratory of Development and Diseases Institute of Biotechnology 100071 Beijing China

Smads is a new gene family in transforming growth factor-β(TGF-β) signaling pathway. Smad2 mutated in multiple human tumors and may be a candidate tumor suppressor gene. Targeted disruption of murine Smad2 gene resulted in embryonic lethality at E6.5. To study the function of Smad2 in vertebrate organgenesis and tumorigenesis, we constructed the Smad2 conditional targeting vector in which two LoxP sequences were placed to flank the sequences encoding the C terminal functional domain of Smad2. The validity of the LoxP sites in the targeting construct was tested in E. coli that express the Cre recombinase constitutively. The vector was electroporated into ES cells and 3 targeted ES cell clones were obtained by Southern blot screening. Targeted ES cells were introduced into C57BL/6J blastocysts by microinjection to generate germ-line chimeras. Genotyping analysis showed that 2 progeny among these chimeras carried the Smad2 conditional targeted allele. The establishment of Smad2 conditional gene targeting mouse has laid a solid foundation for producing the tissue specific Smad2 gene knockout mice.

关键词： Smad2, embryonic stem cell, Cre-LoxP system, conditional gene knockout.

Mechanism and controlling strategy of the production and accumulation of propionic acid for anaerobic wastewater treatment

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2002年第3期45卷 319-327页

作者：任南琪李建政赵丹陈晓蕾 1. Research Center of Environment and biotechnology Harbin Institute of Technology 150090 Harbin China

The production and accumulation of propionic acid affect significantly anaerobic wastewater treatment system, but the reasons are not approached until now. Based on the results of continuous-flow tests and the analysis of biochemistry and ecology, two mechanisms of producing propionic acid have been put forward. It is demonstrated that the reasons of propionic acid production and accumulation are not caused by higher hydrogen partial pressure. The combination of specific pH value and ORP is the ecological factor affecting propionic acid production, and the equilibrium regulation of NADH/NAD+ ratio in cells is the physiological factor. Meanwhile, it is put forward that using the two-phase anaerobic treatment process and the ethanol type fermentation in anaerobic reactor to avoid propionic acid accumulation are efficient methods.

关键词： anaerobic wastewater treatment propionic acid acidogenic ORP(Eh) pH.

Recombination with coat protein transgene in a complementation system based on Cucumber mosaic virus (CMV)

在线全文

学校读者我要写书评

暂无评论

Science China(Life Sciences) 2001年第3期44卷 263-273页

作者：雷万里方荣祥张国华陈晓英张晓勤 1. Laboratory of Plant biotechnology Institute of Microbiology Chinese Academy of Sciences 100080 Beijing China

In order to study the feasibility of Cucumber mosaic virus (CMV) as an expression vector, the full-length cDNA of RNA 3 from strain SD was cloned and the sequence around the start codon of the coat protein (CP) gene was modified to create an Nsi I site for insertion of foreign genes. The CP gene was replaced by the green fluorescent protein (GFP) gene. The cDNAs of Fny RNAs 1.and 2 and the chimeric SD RNA 3 were cloned between the modified 35S promoter and terminator. Tobacco protoplasts were transfected with a mixture of the viral cDNAs containing 35S promoter and terminator as a replacement vector and expressed GFP. A complementation system was established when the replacement vector was inoculated onto the transgenic tobacco plants expressing SD-CMV CP. GFP was detected in the inoculated leaves in 5 of 1. tested plants and in the first upper systemic leaf of one of the 5 plants ten days after inoculation. However, no GFP could be detected in all the plants one month after inoculation. Recombination between the CMV vector and the CP transgene was proved by retro-transcriptional polymerase chain reaction (RT-PCR) and verified by DNA sequencing. Our results argue against the feasibility of the CMV-based replacement vector trans-complemented by the CP transgene, and at the same time, enlighten ways to improve the CMV-based expression vector and the biosafety of CMV CP-mediated virus resistant transgenic plants.

关键词： cucumber mosaic virus complementation vector CP transgene recombination biosafety.

Fine-mapping of an Arabidopsis cell death mutation locus

在线全文

学校读者我要写书评

暂无评论

Science China(Life Sciences) 2000年第2期43卷 138-145页

作者：牟中林戴亚李家洋 1. Plant biotechnology Laboratory Institute of Genetics Chinese Academy of Sciences 100101 Beijing China

An Arabidopsis cell death mutation locus was mapped to chromosome 2 between lGS1.and mi421. The YAC clone ends, CIC9A3R, CIC1.C7L, CIC2G5R and RFLP marker CDs3 within this interval, were used to probe TAMU BAC library and 31.BAC clones were obtained. A BAC contig encompassing the mutation locus, which consists of T6P5, T7M23, T1.A21. T8L6 and T1.A1., was identified by Southern hybridization with the BAC ends as probes. 1. CAPS and 1. STS markers were developed in this region. These results will facilitate map-based cloning of the genes and sequencing of the genomic DNA in this region.

关键词： Arabidopsis cell death mod1 mutant physical map CAPS marker.