羊毛硫肽类化合物(Lanthipeptide)生物合成新进展

羊毛硫肽化合物(Lanthipeptides)是由核糖体合成并经过翻译后修饰得到的一大类肽类天然产物。这类化合物广泛的产生于不同种类的细菌,具有丰富的结构和生物活性多样性,为活性药物研究和开发提供重要的来源。本文综述了近几年来羊毛硫肽化合物生物合成进展,从其合成酶结构,进化机制,区域和立体选择性控制等方面进行了简要的讨论,展示了羊毛硫肽类化合物生物合成中特殊而迷人的酶学机制。     

天然产物中五元杂环生物合成过程的研究进展

五元杂环是指一类含有除碳以外的杂原子的五元环有机化合物,可分为含有一个杂原子的杂环和含有两个杂原子的五元杂环。杂原子通常为氮原子、氧原子或硫原子,在成环时符合休克尔(Hückel)规则,具有芳香性。五元杂环以独特的生物学特性和参与氢键相互作用的能力,成为天然化合物发挥活性功能的重要基团。五元杂环在不同的生物合成途径中有多种环化过程,其前体可以是天然氨基酸、乙酸及乙酰辅酶A等多种形式。将从吡咯、恶唑和噻唑三种五元杂环入手,以代表性化合物为例,对其在生命体中生物合成过程的成环过程进行探讨,为组合生物合成和未知化合物中五元杂环成环过程的研究提供参考。     

植物螯合肽及其在抗重金属胁迫中的作用

植物螯合肽(PCs)广泛存在于植物体中,与植物抗重金属胁迫关系密切。植物螯合肽及其复合物是一类富含半胱氨酸的低分子量化合物。现有研究证明,PCS由谷胱甘肽(GSH)为底物的酶促反应合成,其合成受相关基因的调控,从模式植物拟南芥的突变体中已分离到与PCS合成有关的几个基因。植物螯合肽首先与重金属离子结合形成低分子量(LMW)复合物,以此形态经由细胞质进入液泡后,再与一个分子的植物螯合肽结合,形成对植物组织毒性较小的高分子量(HMW)复合物,从而达到缓解重金属对植物的危害作用。就植物螯合肽及其复合物的结构、生物合成、基因调控及重金属解毒机理等进行了综述,并对今后的研究方向提出了一些看法。     

非核糖体肽合成酶装配机制研究进展CSCD

非核糖体多肽(nonribosomal peptide,NRP)是天然生物活性产物一大类群,组成结构多样,具有多种重要的药用价值。在微生物中催化非核糖体多肽生物合成的是非核糖体肽合成酶(nonribosomal peptide synthetase,NRPS),NRPS是一类模块酶系,模块的组装在非核糖体多肽合成及其环化中起着关键作用。本文主要对非核糖体肽合成酶常规模块组装模式及3种非常规合成模式进行综述,为深入了解和应用非核糖体肽合成酶在抗生素类生物活性物质中的作用提供理论依据。     

紫玉盘中的新内酰胺

从紫玉盘(UvariamicrocarpaChamp.exBenth.)的茎枝分离到7个生物碱,经光谱数据分析鉴定为紫玉盘内酰胺(uvarilactam,1)、马兜铃内酰胺AⅡ(2)、马兜铃内酰胺BⅠ(3)、马兜铃内酰胺BⅡ(4)、马兜铃内酰胺AⅠa(aristololactamAⅠa,5)、4,5_dioxodehydroasimilobine(6)和oxoanolobin(7)。1～5属于菲甲酸内酰胺类化合物,6～7是阿扑菲生物碱类,化合物3与4以混合物出现。其中1是新化合物,其余化合物均首次从该植物中分离得到     

非核糖体肽合成酶装配机制研究进展

非核糖体多肽(nonribosomal peptide,NRP)是天然生物活性产物一大类群,组成结构多样,具有多种重要的药用价值。在微生物中催化非核糖体多肽生物合成的是非核糖体肽合成酶(nonribosomal peptide synthetase,NRPS),NRPS是一类模块酶系,模块的组装在非核糖体多肽合成及其环化中起着关键作用。本文主要对非核糖体肽合成酶常规模块组装模式及3种非常规合成模式进行综述,为深入了解和应用非核糖体肽合成酶在抗生素类生物活性物质中的作用提供理论依据。     

Streptomyces coelicolor A3(2)中新颖Ⅰ型羊毛硫肽的挖掘及异源表达

【目的】Ⅰ型羊毛硫肽通常具有广泛的生物活性,且抑菌机制独特,较少产生耐药性,因而在临床上具有很好的应用前景。本文对Streptomyces coelicolor A3(2)基因组上2个新颖的Ⅰ型羊毛硫肽生物合成基因簇进行研究,以实现目标羊毛硫肽的表达。【方法】首先,通过antiSMASH分析S. coelicolor A3(2)基因组序列,挖掘羊毛硫肽生物合成基因簇,使用BLAST进行基因功能注释,选择可能参与生物合成过程的基因;然后利用基因组装技术构建异源表达质粒,通过接合转移在链霉菌底盘细胞中进行异源表达;最后对发酵产物进行高效液相色谱、质谱及生物活性检测。【结果】通过添加启动子元件重构S. coelicolor A3(2)上基因簇3 (8.9 kb)和基因簇24 (9.0 kb),得到pYES-ColE1-SCO-cluster3和pYES-ColE1-SCO-cluster24。pYES-ColE1-SCO-cluster3在底盘细胞Streptomyces coelicolor M1152和Streptomycessp. A14中成功表达,得到潜在目标化合物coelin 3;pYES-ColE1-SCO-cluster24在底盘细胞Streptomyces sp. ZM13中成功表达,得到潜在目标化合物coelin 24。其中coelin 3对Bacillus subtilis 168和Escherichia coli ATCC 25922具有抑制作用,并且抑菌圈均达到28 mm。【结论】本研究成功使用启动子激活和异源表达策略实现了coelin 3和coelin 24的表达和活性测试,为后续新颖的羊毛硫肽结构解析和作用机制研究奠定了基础。     

放线菌中铁载体生物合成机制研究进展

铁载体是由微生物产生,对铁元素具有高亲和性的小分子化合物。这类天然产物所展现的结构多样性引起人们对其生物合成机制的极大兴趣。目前已有研究报道的铁载体生物合成途径主要有2种,一是直接由非核糖体肽合成酶(Nonribosomal peptide synthetases,NRPSs)家族的多酶复合体负责合成,另一种是以不依赖于NRPS(NRPS-independent,NIS)的方式,由一类特殊合成酶家族参与合成。在过去的十多年中,铁载体生物合成成为天然产物生物合成研究领域的热点之一,其中几种依赖于NRPS途径合成的铁载体生物合成机制已得到充分阐明,而对NIS方式合成的铁载体研究也获得了诸多进展。作为放线菌的一类重要次级代谢产物,通过遗传学、化学等手段对放线菌所产生铁载体生物合成途径的遗传学和生物化学研究,能够为发展新的抗菌药物提供契机,同时也能加深我们对这一类生物活性物质形成机制的认识。综述近期该研究方向的进展。     

大型担子菌中二萜化合物生物合成研究进展

大型担子菌分布广泛,种类繁多,它们是重要的食药用资源的宝库。萜类化合物是其主要活性成分之一,包括倍半萜、二萜和三萜等,这些化合物具有预防、缓解或治疗癌症、抑郁症、糖尿病和高脂血症等多种疾病的功效。目前,从担子菌中分离出的二萜类化合物基本骨架结构特征主要为鸟巢烷(cyathanes)型、截短侧耳素(pleuromutilins)型、guanacastanes型、海松烷(pimaranes)型、松香烷(abietanes)型和毛皮伞烷(crinipellins)型6大类型。本文综述了担子菌中二萜类化合物的结构特点、生物活性和生物合成的研究进展,对参与担子菌中二萜化合物生物合成的二萜合成酶进行了分类,对两种重要的二萜化合物生物合成途径进行了系统总结和论述。本文将为未知二萜化合物生物合成途径及关键基因功能解析提供参考。     

聚酮类抗生素生物合成基因簇间的关系

<正>放线菌基因组测序显示基因组中平均有超过20个以上的次生代谢生物合成基因簇,但通常放线菌在试验条件下能检测到的产物仅有2-3个,因此这些次生代谢生物合成基因簇引起了研究者的极大关注,期望通过基因组的挖掘来发现新的代谢产物。除虫链霉菌(Streptomyces avermitilis)产生的16元大环内酯化合物阿维菌素及衍生物被广泛用于防治动植物的线虫类和节肢动物类害虫[1-2]。除虫链霉菌的基因组中,除了阿维菌素生物合成基因簇外,还有其它11种聚酮合成酶类(Polyketide synthesase,PKS)抗生素生物合成基因簇[3]。由于聚酮化合物生物合     

Biologically active oxylipins from seaweeds

Our previous research has shown that many red algae metabolize polyunsaturated fatty acids to oxidized products resembling the eicosanoid hormones from mammals. We have extended these studies to members of the Phaeophyceae and Chlorophyta and find they also possess similar biosynthetic pathways. From several we have identified novel prostaglandin-like substances. Studies of the molecular mechanisms by which some of these marine oxylipins are formed have revealed that novel oxidative reactions are utilized. Understanding of these biosynthetic pathways in detail has allowed their utilization to produce research biochemicals of high value, such as 12S-hydroperoxyeicosatetraenoic acid (12S-HPETE). Because of their biological properties, seaweed-derived oxylipins have potential utility as pharmaceuticals and research biochemicals.     

Gibberellin biosynthesis in fungi: genes, enzymes, evolution, and impact on biotechnology

Gibberellins (GAs) constitute a large family of tetracyclic diterpenoid carboxylic acids, some members of which function as growth hormones in higher plants. As well as being phytohormones, GAs are also present in some fungi and bacteria. In recent years, GA biosynthetic genes from Fusarium fujikuroi and Arabidopsis thaliana have been cloned and well characterised. Although higher plants and the fungus both produce structurally identical GAs, there are important differences indicating that GA biosynthetic pathways have evolved independently in higher plants and fungi. The fact that horizontal gene transfer of GA genes from the plant to the fungus can be excluded, and that GA genes are obviously missing in closely related Fusarium species, raises the question of the origin of fungal GA biosynthetic genes. Besides characterisation of F. fujikuroi GA pathway genes, much progress has been made in the molecular analysis of regulatory mechanisms, especially the nitrogen metabolite repression controlling fungal GA biosynthesis. Basic research in this field has been shown to have an impact on biotechnology. Cloning of genes, construction of knock-out mutants, gene amplification, and regulation studies at the molecular level are powerful tools for improvement of production strains. Besides increased yields of the final product, GA₃, it is now possible to produce intermediates of the GA biosynthetic pathway, such as ent-kaurene, ent-kaurenoic acid, and GA₁₄, in high amounts using different knock-out mutants. This review concentrates mainly on the fungal biosynthetic pathway, the genes and enzymes involved, the regulation network, the biotechnological relevance of recent studies, and on evolutionary aspects of GA biosynthetic genes.     

Characterization of the bagremycin biosynthetic gene cluster in Streptomyces sp. Tü 4128

Bagremycin A and bagremycin B isolated from Streptomyces sp. Tü 4128 have activities against Gram-positive bacteria, fungi and also have a weak antitumor activity, which make them have great potential for development of novel antibiotics. Here, we report a draft genome 8,424,112 bp in length of S. sp. Tü 4128 by Illumina Hiseq2000, and identify the bagremycins biosynthetic gene cluster (BGC) by bioinformatics analysis. The putative bagremycins BGC includes 16 open reading frames (ORFs) with the functions of biosynthesis, resistance and regulation. Disruptions of relative genes and HPLC analysis of bagremycins production demonstrated that not all the genes within the BGC are responsible for the biosynthesis of bagremycins. In addition, the biosynthetic pathways of bagremycins are proposed for deeper inquiries into their intriguing biosynthetic mechanism.     

假单胞菌生物被膜核心胞外多糖生物合成系统研究进展

胞外多糖是假单胞菌生物被膜的重要组成部分,能增强菌体对外界环境、抗菌剂和宿主防御的耐受性.假单胞菌能产生3种与生物被膜形成密切相关的核心胞外多糖:褐藻胶、Psl和Pel,它们在细菌细胞中的合成和转运分别依赖对应的褐藻胶、Psl和Pel生物合成系统.因此,本综述系统全面地总结了假单胞菌3种胞外多糖生物合成系统结构生物学的...     

Understanding insect endocrine systems: molecular approaches

Molecular approaches have led to spectacular improvement of our knowledge of insect endocrinology. The present review focuses on two major classes of insect lipidic hormones, ecdysteroids and juvenile hormones. Although the ecdysteroid biosynthetic pathway is not yet fully elucidated, several new steps have been recently characterized, and molecular studies of biosynthetic enzymes are now beginning. It is expected that, thanks to suitable biological models (e.g., ecdysteroid-defective mutants of Drosophila), the entire biosynthetic pathway will be elucidated in the near future. The understanding of the ecdysteroid mode of action has benefited from studies with Drosophila and major developments relate to the cascades of gene activation and the molecular basis for the stage- and tissue-specificity of hormonal effects. The biosynthetic pathway of juvenile hormones is fully known, but molecular studies of enzymes are still in their infancy, and there is some controversy about the nature of juvenile hormone receptors. Within the forthcoming years, molecular tools will allow to characterize all the enzymes involved in hormone biosynthesis and then to analyze the fine regulation of hormone titers. They will also allow comparative studies aimed at investigating the presence of related molecules (hormone biosynthetic enzymes and receptors) among other Invertebrates (Arthropods and non-Arthropods), and thus to propose evolutionary scenarios for their endocrine systems.     

Regulation of plant glucosinolate metabolism

Glucosinolates and their degradation products are known to play important roles in plant interaction with herbivores and micro-organisms. In addition, they are important for human life. For example, some degradation products are flavor compounds and some exhibit anticarcinogenic properties. Recent years have seen great progress made in the understanding of glucosinolate biosynthesis in Arabidopsis thaliana. The core glucosinolate biosynthetic pathway has been revealed using biochemical and reverse genetics approaches. Future research needs to focus on questions related to regulation and control of glucosinolate metabolism. Here we review current status of studies on the regulation of glucosinolate metabolism at different levels, and highlight future research towards elucidating the signaling and metabolic network that control glucosinolate metabolism.     

An in vitro system to study cyclopeptide heterophyllin B biosynthesis in the medicinal plant <Emphasis Type="Italic">Pseudostellaria heterophylla</Emphasis>

Plant cyclopeptides are a large group of small molecule metabolites found in a wide variety of plants, including traditional Chinese medicinal plants. Many of the cyclopeptides have highly unusual structures and potent biological activities. However, the majority of the cyclopeptides have not been studied for their biosynthetic mechanisms. In this study, we have established a culture system for the biosynthetic study of heterophyllin B (HB), a cyclopeptide produced by the medicinal plant Pseudostellaria heterophylla. We first developed a shoot culture of P. heterophylla that produced HB consistently under laboratory conditions. Using ¹⁴C-labeled proline as tracer, we showed that labeled HB was produced by the cultured shoots, indicating that this system has de novo biosynthetic activity. Next, we chemically synthesized HB’s linear peptide precursor (LHB) and the N-acetyl cysteamine thioester of LHB (LHB-SNAC). When LHB-SNAC was incubated with total cell free extracts of the cultured shoots, a small amount of cyclized product (HB), in addition to the hydrolyzed product (LHB), was produced. The in vivo and in vitro results demonstrate the presence of an HB biosynthetic system, which provides insight into the molecular mechanism for plant cyclopeptide biosynthesis.     

The crystal structure of AbsH3: A putative flavin adenine dinucleotide‐dependent reductase in the abyssomicin biosynthesis pathway

Natural products and natural product‐derived compounds have been widely used for pharmaceuticals for many years, and the search for new natural products that may have interesting activity is ongoing. Abyssomicins are natural product molecules that have antibiotic activity via inhibition of the folate synthesis pathway in microbiota. These compounds also appear to undergo a required [4 + 2] cycloaddition in their biosynthetic pathway. Here we report the structure of an flavin adenine dinucleotide‐dependent reductase, AbsH3, from the biosynthetic gene cluster of novel abyssomicins found in Streptomyces sp. LC‐6‐2.     

短梗霉产liamocins研究进展

短梗霉真菌(Aureobasidium spp.)是一种世界性的酵母样真菌,因其产生黑色素而被称为黑酵母.短梗霉的许多菌株都能分泌细胞外脂质liamocins.Liamocins具有表面活性、良好的抗癌和抗菌活性.本文综述了分泌liamocins的短梗霉的多样性及影响其产生liamocins的因素,总结了liamoci...