细菌的磷酸转移酶系统ppt课件

1、细菌的磷酸转移酶系统Bacterial Phosphotransferase System Bacteria are thrifty cells. They often live in inhospitable environments, and many live in places with no oxygen, so their options for generating energy are limited. So, bacteria have developed many clever ways of living off of whatever is available, and

2、 exploiting these resources to their best advantage. The bacterial phosphotransferase system, often abbreviated as PTS, is a perfect example of both the opportunistic nature of bacterial life, and their thrifty use of resources. 注释： 细菌是种节省的细胞生物体。他们通常都在恶劣的环境当中生存，甚至许多生存在没有氧气的地方，所以他们产生能量的方式选择非常有限。因此细菌本

3、身培育了许多巧妙的方法以顺应接触的任何环境，以及开发这些资源于本身以最好的利用。细菌的磷酸转移酶系统，通常缩写为PTS，无论是对细菌生活的多时机自然环境，还是他们节省运用的资源，都是一个完美的例子。Leading ：细菌中糖的磷酸转移酶功能发现 In 1964, Kundig, Ghosh and Roseman reported the discovery of the PEP: sugar phosphotransferase system (PTS). Thirty years later, we find that the PTS functions not only as a sug

4、ar-phosphorylating system, but also as a complex protein kinase复合蛋白激酶 system that regulates调理 a wide variety of metabolic新陈代谢的 processes and controls the expression of numerous大量 genes. As a result of recent operon- and genome-sequencing projects, novel新的 PTS protein-encoding编码 genes have been disco

5、vered, most of which have yet to be functionally defined. Some of them appear to be involved in cellular细胞的 processes distinct from those recognized previously先前的. Fundamental aspects of past and current PTS research are briefly reviewed, and recent advances增长 are integrated整合 into conceptual pictur

6、es that provide guides for future research. How Phosphotransferase System-Related Protein Phosphorylation Regulates Carbohydrate Metabolism糖类新陈代谢系统 in Bacteria 蛋白的磷酸化及去磷酸化形状在分解物代谢阻遏中起关键作用。PTS系统是运载体家族中的转位分子，在原核生和古细菌中广泛存在。大肠杆菌主要经过PEPsugar PTS以集团转移方式进展葡萄糖的摄取， PTS包括EI，HPr，EII。前两者为胞质可溶型蛋白，无底物识别特异性。分别由pst

7、I，pstH支配子编码，后者多为蛋白复合体，对碳水化合物具有识别特异性,可特异性识别和转运底物分子，E.coli编码约20种Es，涉及20多种不同碳化物磷酸化转运。Hpr: histidine-containing phosphocarrier protein含组氨酸的磷含组氨酸的磷酸载体蛋白酸载体蛋白 EI：extract(获得获得) the phosphate from PEP and adds it to the carrier protein, HPr.EII：分为：分为EIIA,EIIB,EIIC类别，有时类别，有时EIIC又会连又会连带上带上EIID磷酸转移酶系统蛋白磷酸转移酶系统

8、蛋白-蛋白复合体的三维构造蛋白复合体的三维构造 PTS的作用过程：的作用过程： EI先从先从PEP处获得磷酸处获得磷酸基团，并将其加载到载基团，并将其加载到载体蛋白体蛋白HPr上，然后载体上，然后载体蛋白将磷酸基团传送给蛋白将磷酸基团传送给整个系列当中相对应不整个系列当中相对应不同的转运蛋白。磷酸基同的转运蛋白。磷酸基团在几种蛋白当中穿越，团在几种蛋白当中穿越，从从HPr挪动到挪动到EIIA，再到，再到EIIB ，最终到达处在，最终到达处在EIIC有时会带上一个有时会带上一个额外的链额外的链EIID当中的当中的葡萄糖。每个转运蛋白葡萄糖。每个转运蛋白由由EII蛋白本身的各个集蛋白本身的各个集成

9、物组成，有时会作为成物组成，有时会作为隔离蛋白，有时又会在隔离蛋白，有时又会在一个长链蛋白质中作为一个长链蛋白质中作为一连串相互连结的构造一连串相互连结的构造区域区域 磷酸化的HPr是一个一切PTS中EII的磷酸通用供体。这个磷酸转移活性伴随着从PTS系列的通用磷酸转移部分到葡萄糖特异的那条途径。而葡萄糖特异的载体IIAGlc这个蛋白不仅作为葡萄糖转移过程中的中间体，同时也作为非PTS通透酶和腺苷酸环化酶的调理者。HPrIIAGlc复合体的构造是采用同位素标志蛋白质的组合，利用多维 异核NMR光谱技术解析的。 Carbohydrate transport and phosphorylation

10、 by the PTS and their coupling to glycolysis. Carbohydrates are transported and concomitantly phosphorylated by the PTS. The phosphorylated carbohydrate feeds into glycolysis, normally at the glucose-6-P or fructose-6-P level. Two phosphoenolpyruvate molecules are usually formed in glycolysis, one o

11、f which is used to drive the transport and initial phosphorylation of the carbohydrate. As a result, the phosphorylation state of the PTS proteins depends on both the concentration of extracellular carbohydrates and the ratio of internal phosphoenolpyruvate and pyruvate. Abbreviations for enzymes (i

12、n boldface type) are as follows: Pgi, phosphoglucose isomerase; Pfk, phosphofructokinase; Fba, fructose-1,6-bisphosphate aldolase; Tpi, triose-phosphate isomerase; Gap, glyceraldehyde-3-phosphate dehydrogenase; Pgk, phosphoglycerate kinase; Pgm, phosphoglycerate mutase; Eno, enolase; Pyk, pyruvate k

13、inase. 醛糖代谢PTS作用机制作用机制Self-priming Pump 自吸泵能量 The phosphotransferase system is particularly energy-efficient when compared to many of the other transport systems in the cell. Many transporters use ATP to power the import of nutrients, but PTS transporters also add a phosphate group to them at the sa

14、me time. Instead of ATP, a molecule of PEP is used to power激活激活 the PTS reaction and provide the phosphate. This pre-phosphorylation of sugars糖的磷酸前体物糖的磷酸前体物 primes指点指点them for entry into the energy production pathways.Harvesting Resources 收获资源 The phosphotransferase system is built around a collecti

15、on of specific transporters that import resources into the cell. PSI researchers have recently revealed the structure of one of these transporters, which imports a disaccharide双糖双糖. Typical bacterial cells make many similar transporters (E. coli has at least 15) that all stand ready to import whatev

16、er sugars are available. A complex regulatory network decides which transporters are expressed and used at any given time. PST系统是一些特定运输物组建的集合体，这些运输物会向系统是一些特定运输物组建的集合体，这些运输物会向细胞中输入资源。细胞中输入资源。PSI研讨者最近发现了这些运输物之一构研讨者最近发现了这些运输物之一构造，此构造是向细胞内输入双糖。典型的细菌细胞有许多类造，此构造是向细胞内输入双糖。典型的细菌细胞有许多类似的转移物似的转移物(E. coli 至少至少

17、15，无论糖类能否便于利用他们，无论糖类能否便于利用他们都时辰做好预备向内输入。一个复杂的调控系统网络决议着都时辰做好预备向内输入。一个复杂的调控系统网络决议着在特定时间中哪一种转运物被表达或被利用。在特定时间中哪一种转运物被表达或被利用。Modular模块化，单元化Reaction The modular nature of the EI and EII proteins allows the same energy production machinery to power many different sugar transporters. PSI researchers have de

18、termined the structures of several different forms of the EIIB protein from different organisms and from different sugar transport complexes.研讨方法研讨方法对于包含在经过对于包含在经过PTS进展磷酸转移的过进展磷酸转移的过程以及程以及PTS蛋白参与调控过程的机制蛋白参与调控过程的机制的了解在很大程度上是经过蛋白组分的了解在很大程度上是经过蛋白组分的相互作用的种类的三维构造的可视的相互作用的种类的三维构造的可视化来实现的。人们曾经利用化来实现的。人们曾经利用X衍射晶体衍射晶体学和学和NMR核磁共振对核磁共振对PTS的单个的单个的蛋白酶的蛋白酶I、HPr、IIA进展了广泛进展了广泛的特征分析。然而，除了甘油激酶的特征分析。然而，除了甘油激酶IIAGlc复合体，没有一个复合体