植物代谢组学研究进展

代谢组学是继基因组学、转录组学和蛋白质组学之后发展起来的一门学科,通过对细胞内的基因表达最终代谢产物的定性和定量分析以及定义细胞或器官的生化表现类型来解释功能基因的表达过程。文中就代谢组学的发展历史、主要研究内容、技术特点、数据处理过程及在植物领域中的应用的最新进展几方面进行阐述,以供读者参考。     

代谢物组学的研究进展

结构基因组学、蛋白质组学和转录物组学的研究产生了大量关于基因表达和蛋白质表达的数据,但同时,它们与功能基因组学的研究相比也显示出了局限性。与之相对,生物体内代谢物组的研究有广阔的前景,这便随之产生了代谢物组学。本系统地综述了代谢物组学的最新发展动态,主要包括代谢物组学的研究内容、研究手段及其应用领域等方面。     

Glycosyltransferases:key players involved in the modification of plant secondary metabolites

Glycosyltransferases are members of the multigene superfamily in plants that can transfer single or multiple activated sugars to a range of plant molecules,resulting in the glycosylation of plant compounds.Although the activities of many glycosyltransferases and their products have been recognized for a long time,only in recent years were some glycosyltransferase genes identified and a few functionally characterized in detail.Glycosylation is thought to be one of the most important modification reactions towards plant secondary metabolites,and plays a key role in maintaining cell homeostasis,thus likely participating in the regulation of plant growth,development and in defense responses to stress environments.With advances in plant genome projects and the development of novel technologies in analyzing gene function,significant progress could be made in gaining new insights into the properties and precise biological roles of plant secondary product glycosyltransferases,and the new knowledge will have extensive application prospects in the catalytic synthesis of glycoconjugates and metabolic engineering of crops.In this review,we summarize the current research,highlighting the possible biological roles,of plant secondary metabolite glycosyltransferases and discuss their potential applications as well as aspects to be further studied in the near future.     

Glycosyltransferases: key players involved in the modification of plant secondary metabolites

Glycosyltransferases are members of the multigene superfamily in plants that can transfer single or multiple activated sugars to a range of plant molecules, resulting in the glycosylation of plant compounds. Although the activities of many glycosyltransferases and their products have been recognized for a long time, only in recent years were some glycosyltransferase genes identified and a few functionally characterized in detail. Glycosylation is thought to be one of the most important modification reactions towards plant secondary metabolites, and plays a key role in maintaining cell homeostasis, thus likely participating in the regulation of plant growth, development and in defense responses to stress environments. With advances in plant genome projects and the development of novel technologies in analyzing gene function, significant progress could be made in gaining new insights into the properties and precise biological roles of plant secondary product glycosyltransferases, and the new knowledge will have extensive application prospects in the catalytic synthesis of glycoconjugates and metabolic engineering of crops. In this review, we summarize the current research, highlighting the possible biological roles, of plant secondary metabolite glycosyltransferases and discuss their potential applications as well as aspects to be further studied in the near future.     

植物类胡萝卜素代谢工程与应用

类胡萝卜素是人类所需要的重要营养成分之一,不仅具有抗氧化、预防肿瘤和心血管等疾病的作用,而且还是人体合成维生素A的前体。全球大约有280万～330万学龄前儿童出现维生素缺乏（vitaminAdeficiency,VAD）的临床症状;近2亿儿童处于半缺乏状态。通过对植物类胡萝卜素生物合成途径的解析,以及对参与这一代谢过程的酶及其调控机制的深入了解,目前已经可以通过基因工程在主要农作物中组织特异性地促进类胡萝卜素的合成与积累。从理论上已经可以利用转基因植物来减少VAD的出现。该文简要回顾近年来这一领域的研究进展。     

A modular modulation method for achieving increases in metabolite production

Increasing the production of overproducing strains represents a great challenge. Here, we develop a modular modulation method to determine the key steps for genetic manipulation to increase metabolite production. The method consists of three steps: (i) modularization of the metabolic network into two modules connected by linking metabolites, (ii) change in the activity of the modules using auxiliary rates producing or consuming the linking metabolites in appropriate proportions and (iii) determination of the key modules and steps to increase production. The mathematical formulation of the method in matrix form shows that it may be applied to metabolic networks of any structure and size, with reactions showing any kind of rate laws. The results are valid for any type of conservation relationships in the metabolite concentrations or interactions between modules. The activity of the module may, in principle, be changed by any large factor. The method may be applied recursively or combined with other methods devised to perform fine searches in smaller regions. In practice, it is implemented by integrating to the producer strain heterologous reactions or synthetic pathways producing or consuming the linking metabolites. The new procedure may contribute to develop metabolic engineering into a more systematic practice. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:656–667, 2015     

Tastes of L-Glutamyl Oligopeptides in Relation to Their Chromatographic Properties

Twelve L-glutamyl dipeptides were prepared and on the basis of their tastes were classified into three groups: I brothy taste group (Glu-Asp, Glu-Thr, Glu-Ser and Glu-Glu); II flat taste group (Glu-Gly, Glu-Ala, Glu-Pro and Glu-Val); and III bitter taste group (Glu-Ile, Glu-Leu, Glu-Tyr and Glu-Phe). Examination with ion-exchange, thin layer and paper partition chromatographies showed that the dipeptides in I were more acidic, polar and hydrophilic than those in II, the bitter dipeptides (III) being rather hydrophobic. Similar tests for a brothy taste tripeptide, Glu-Gly-Ser, indicated that this possessed properties resembling I. O-Acetylation of the serine residue of Glu-Gly-Ser lessened its hydrophilicity and the taste became flat. The O-butyrylation resulted in a marked increase in hydrophobicity and the product showed a bitter taste.