氨基糖苷类抗生素生物合成基因研究进展

目的对氨基糖苷类抗生素生物合成基因的研究进展作一综述。方法按照化学结构类型 ,分别介绍了有糖苷取代的氨基环己醇类抗生素和 2 脱氧链霉胺类抗生素的生物合成基因的研究状况 ,以及氨基糖苷类抗生素生物合成基因的特点。结果与结论氨基糖苷类抗生素生物合成基因具有很多共同的特点 ,为进一步对氨基糖苷类抗生素生物合成基因进行克隆、研究及基因改造提供了参考     

抗生素糖基转移酶研究进展

糖苷类抗生素是临床上广泛应用的抗菌和抗肿瘤化合物。该类化合物在体内由糖基转移酶催化，糖基化反应通常在抗生素生物合成的最后发生，糖基的位置、类型和数量对糖苷类抗生素的活性有很大的影响。本文综述了糖基转移酶的种类、功能、特性及其在组合生物合成中的应用与研究前景。     

2-脱氧链霉胺类抗生素生物合成基因的研究进展

含2-脱氧链霉胺类（2-DOS）氨基糖苷抗生素是临床常用抗生素。近几年对2-脱氧链霉胺类抗生素的分子水平研究取得重大进展，得到了2-DOS合成中的关键酶基因，以及丁酰苷菌素、妥布霉素、卡那霉素、庆大霉素等部分生物合成基因簇克隆。本文对2-脱氧链霉胺类抗生素生物合成基因研究进展进行了综述。     

海洋链霉菌Streptomyces parvus SCSIO Mla-L010中大环内酰胺类抗生素vicenistatin的糖基定向改造

目的 利用海洋链霉菌Streptomyces parvus SCSIO Mla-L010中糖基转移酶的底物宽泛性对vicenistatin进行糖基定向化改造.方法 采用组合生物合成技术分别将其他糖苷类天然产物生物合成途径中的糖基合成基因导入到SCSIO Mla-L010菌株中,构建糖基合成基因异源表达重组菌株;以有机溶...     

灰色链霉菌的链霉素基因簇和卡那霉素抗性序列在某种菌株和菌种间的差别

现在已知抗生素的产生不是菌种异同而是菌株差异而不同。尽管对抗生素生物合成和调节作了大量研究,但对涉及产生抗生素菌株的有关生物化学和遗传学基础研究甚少。研究表明产生氨基糖苷类抗生素(AG)菌株具有与其相关的AG抗性类型,已证明许多抗生素产生菌的生物合成基因和其抗生素抗性基因遗传结构连锁。灰色链霉菌包括产生多种类型抗生素的菌株,如链霉素(SM),金霉素,和灰霉素产生菌。在灰色链霉菌中,各菌株具有较高的DNA同源性,但各菌株产生抗生素的遗传     

氨基糖苷类钝化酶耐药机制的研究进展

氨基糖苷类抗生素的耐药机制相当复杂，其中以产生钝化酶为主，近来对其研究较多，尤其是分子水平的研究取得了一些进展。本文对三种主要钝化酶即氨基糖苷磷酸转移酶、氨基糖苷乙酰转移酶、氨基糖苷类核苷转移酶的作用底物、作用位点、常见耐药细菌、编码基因等进行综述。     

合成培养基内新抗癌抗生素——四制癌素A的产生及生物合成

四制癌素 A(TetrocarcinA)是青铜色小单孢菌产生的一种新的抗生素,具有由非糖部份、四内酯(Tetronoliole)、硝基糖,三个地芰毒糖以及二个友菌糖所组成的结构,其生物合成很有研究意义。小单孢菌属产生数类抗生素,例如氨基糖苷类及大环内酯类,但是产生四制癌素类抗生素尚无报道。用合成培养基可以测定影响生长及抗生素产生的因素,用以阐明四制癌素类的生化途径。本文叙述合成培养基配制,四制癌素 A 产生的必需条件以及讨论其生物合成。     

调节博来霉素生物合成基因的研究进展

博来霉素为氨基糖肽类抗肿瘤抗生素,具有良好的抗肿瘤活性。本文介绍了博来霉素生物合成基因的研究进展,包括博来霉素生物合成基因各基因的结构和功能、BlmIX／BlmⅧ／BlmⅦ组成的杂合系统和磷酸泛酰巯基乙胺基转移酶对杂合系统中的载体蛋白的翻译后修饰作用。     

太乐菌素生产的遗传与生化

太乐菌素是一种由弗氏链霉菌产生的16员的大环内酯抗生素.由一个分支内酯(太乐糖苷)和三个糖(mycaminose,mycarose及mycinose)组成的.作者感兴趣的是(1)遗传修饰弗氏链霉菌改良太乐菌素生产;(2)测定遗传定位以及太乐菌素结构基因潜在群集型;(3)测定太乐菌素生物合成途径以及鉴别限制步骤的速率;(4)应用各种遗传技术建造重组体菌株生产杂种大环内酯抗生素.本文讨论太乐菌素生物合成障碍突变体研究推导的关于太乐菌素生物合成途径目前情况.同时扼要地讨论太乐菌素结构基因图     

抗生素产生菌核糖体相关基因改变与次级代谢产物的生物合成

利用抗生素抗性筛选方法及定点突变方法可以得到引起抗生素产生菌核糖体相关基因改变的突变株,这些突变对次级代谢产物的生物合成产生深刻影响,如能够显著地提高抗生素的产量也能够产生一些新的次级代谢产物。这种方法不仅对抗生素产生菌的菌种选育具有重要的意义,且为获得新的抗生素提供了新的途径。本文就抗生素产生菌核糖体蛋白基因、核糖体RNA基因、核糖体修饰相关基因及核糖体相关蛋白基因的改变引起次级代谢改变研究进展做简要综述。     

Cloning of the biosynthetic gene cluster for naphthoxanthene antibiotic FD-594 from Streptomyces sp. TA-0256

FD-594 is an unique pyrano[4',3':6,7]naphtho[1,2-b]xanthene polyketide with a trisaccharide of 2,6-dideoxysugars. In this study, we cloned the FD-594 biosynthetic gene cluster from the producer strain Streptomyces sp. TA-0256 to investigate its biosynthesis. The identified pnx gene cluster was 38143 bp, consisting of 40 open reading frames, including a minimal PKS gene, TDP-olivose biosynthetic genes, two glycosyltransferase genes, two methyltransferase genes and many oxygenase/reductase genes. Most of these enzymes coded in the pnx cluster were reasonably assigned to a plausible biosynthetic pathway for FD-594, in which an unique ring opening process via Baeyer-Villiger-type oxidation catalyzed by a putative flavin adenine dinucleotide (FAD)-dependent monooxygenase, is speculated to lead to the unique xanthene structure. To clarify the involvement of pnx genes in the FD-594 biosynthesis, a glycosyltransferase, PnxGT2, and a methyltransferase, PnxMT2, were characterized enzymatically with the recombinant proteins expressed in Escherichia coli. As a result, PnxGT2 catalyzed the triple olivose transfers to the FD-594 aglycon with TDP-olivose as the glycosyl donor to afford triolivoside. Surprisingly, in the PnxGT2 enzymatic reaction, tetraolivoside and pentaolivoside were significantly detected along with the expected triolivoside. To our knowledge, PnxGT2 is the first contiguous oligosaccharide-forming glycosyltransferase in secondary metabolism. Furthermore, addition of PnxMT2 and S-adenosyl-L-methionine into the PnxGT2 reaction mixture afforded natural FD-594 to confirm that the PnxGT2 reaction product was the expected regiospecifically glycosylated compound. Consequently, the identified pnx gene cluster appears to be involved in FD-594 biosynthesis.     

Bifunctional penicillin-binding proteins: focus on the glycosyltransferase domain and its specific inhibitor moenomycin

Beta-lactams and glycopeptides antibiotics directed against enzymes involved in bacterial cell wall synthesis have generated bacterial resistance. Search for new antibiotic molecules is widely focused on bifunctional Penicillin-Binding Proteins (PBPs), with particular emphasis on their glycosyltransferase activity. This function catalyzes glycan chain polymerization of the cell wall peptidoglycan. This review summarizes recent results about biochemical characterization of bifunctional PBPs and enzymatic properties of the glycosyltransferase domain. Moenomycin, a well studied glycosyltransferase activity inhibitor has provided useful informations about lipid binding properties and about cellular role of bifunctional PBPs. These enzymes were shown to be a part of the multienzymatic complex involved in peptidoglycan biosynthesis. Furthermore, bifunctional PBPs are also present in the protein complex located at the site of septation during cell division. The glycosyltransferase domain of bifunctional PBPs remains unsufficently characterized: the structural analysis may lead to the development of novel antibacterials and to the understanding of the enzymatic properties, while genetic and cellular studies focused on bifunctional PBPs will provide a wealth of knowledge regarding cell growth and division.     

Identification of L-glutamine: 2-deoxy-scyllo-inosose aminotransferase required for the biosynthesis of butirosin in Bacillus circulans

Using inverse PCR, two new genes (btrN and btrS) were identified upstream of the putative glycosyltransferase gene btrM in the butirosin-biosynthetic btr gene cluster of Bacillus circulans. The upstream gene btrS showed significant homology with stsC of Streptomyces griseus, which encodes L-glutamine:scyllo-inosose aminotransferase in the biosynthesis of streptomycin. The function of BtrS was further confirmed by heterologous expression in Escherichia coli and chemical identification of the conversion of 2-deoxy-scyllo-inosose into 2-deoxy-scyllo-inosamine. The identification of BtrS as L-glutamine:2-deoxy-scyllo-inosose aminotransferase is the first report of the aminotransferase gene responsible for 2-deoxystreptamine biosynthesis.     

Molecular analysis of tlrB, an antibiotic-resistance gene from tylosin-producing Streptomyces fradiae, and discovery of a novel resistance mechanism.

The tlrB gene, which confers inducible resistance to a range of macrolide antibiotics including biosynthetic precursors of tylosin, was isolated and sequenced. In the genome of Streptomyces fradiae, it lies between pbp, which encodes a putative penicillin-binding protein, and tylN, encoding a glycosyltransferase involved in tylosin biosynthesis. The TlrB protein was produced in E. coli as a fusion to MalE. The fusion protein, but not MalE alone, inactivates macrolides in the presence of S-adenosyl-methionine (SAM) but the modified product(s) has not been characterised.     

浸麻芽孢杆菌环糊精葡糖基转移酶的克隆与表达

目的获取浸麻芽孢杆菌环糊精葡糖基转移酶基因并在大肠杆菌中表达。方法构建浸麻芽孢杆菌环糊精葡糖基转移酶表达质粒,转化大肠杆菌DH5α,筛选获得阳性重组菌株。经42℃诱导后,检测酶活性。结果浸麻芽孢杆菌环糊精葡糖基转移酶在大肠杆菌中成功表达,表达量达3 U/mL。结论浸麻芽孢杆菌环糊精葡糖基转移酶可以在大肠杆菌中高效表达。     

E. Coli MurG: a paradigm for a superfamily of glycosyltransferases

MurG is an essential bacterial glycosyltransferase that is involved in the biosynthesis of peptidoglycan. The enzyme is found in all organisms that synthesize peptidoglycan and is a target for the design of new antibiotics. A direct assay to study MurG was reported recently, followed shortly by the crystal structure of E. coli MurG. This first MurG structure, combined with sequence data on other glycosyltransferases, has revealed that MurG is a paradigm for a large family of metal ion-independent glycosyltransferases found in both eukaryotes and prokaryotes. A better understanding of MurG could lead to the development of new drugs to combat antibiotic resistant infections, and may also shed light on a broad class of glycosyltransferases.     

Cloning of the pactamycin biosynthetic gene cluster and characterization of a crucial glycosyltransferase prior to a unique cyclopentane ring formation

The biosynthetic gene (pct) cluster for an antitumor antibiotic pactamycin was identified by use of a gene for putative radical S-adenosylmethionine methyltransferase as a probe. The pct gene cluster is localized to a 34 kb contiguous DNA from Streptomyces pactum NBRC 13433 and contains 24 open reading frames. Based on the bioinformatic analysis, a plausible biosynthetic pathway for pactamycin comprising of a unique cyclopentane ring, 3-aminoacetophenone, and 6-methylsalicylate was proposed. The pctL gene encoding a glycosyltransferase was speculated to be involved in an N-glycoside formation between 3-aminoacetophenone and UDP-N-acetyl-alpha-D-glucosamine prior to a unique cyclopentane ring formation. The pctL gene was then heterologously expressed in Escherichia coli and the enzymatic activity of the recombinant PctL protein was investigated. Consequently, the PctL protein was found to catalyze the expected reaction forming beta-N-glycoside. The enzymatic activity of the PctL protein clearly confirmed that the present identified gene cluster is for the biosynthesis of pactamycin. Also, a glycosylation prior to cyclopentane ring formation was proposed to be a general strategy in the biosynthesis of the structurally related cyclopentane containing compounds.     

主动靶向脂质体在抗肿瘤治疗中的研究进展

主动靶向脂质体给药系统可使抗肿瘤药物与靶组织结合,将药物可控性地分布于靶组织并持续缓慢释药,在提高药物抗癌效果的同时,降低了其对正常组织的不良反应。本文主要介绍了免疫脂质体、受体介导的脂质体、糖基修饰的脂质体及多肽修饰的脂质体等主动靶向脂质体在抗肿瘤研究中的进展。主动靶向脂质体给药系统将会发展为抗肿瘤药物的理想剂型,具有很好的临床应用前景。