細菌的磷酸轉移酶系統(tǒng)

1、細菌的磷酸轉移酶系統(tǒng)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. 注釋： 細菌是種節(jié)儉的細胞生物體。他們通常都在惡劣的環(huán)境當中生存，甚至許多生存在沒有氧氣的地方，所以他們產生能量的方式選擇非常有限。因此細菌自

3、身培養(yǎng)了許多巧妙的方法以適應接觸的任何環(huán)境，以及開發(fā)這些資源于自身以最好的利用。細菌的磷酸轉移酶系統(tǒng)，通?？s寫為pts，無論是對細菌生活的多機會自然環(huán)境，還是他們節(jié)儉使用的資源，都是一個完美的例子。leading ：細菌中糖的磷酸轉移酶功能發(fā)現(xiàn) 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（復合蛋白激酶） system that regulates（調節(jié)） a wide variety of metabolic（新陳代謝的） 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編碼 genes have be

5、en discovered, most of which have yet to be functionally defined. some of them appear to be involved in cellular細胞的 processes distinct from those recognized previously先前的. fundamental aspects of past and current pts research are briefly reviewed, and recent advances增長 are integrated整合 into conceptua

6、l pictures that provide guides for future research. how phosphotransferase system-related protein phosphorylation regulates carbohydrate metabolism（糖類新陳代謝系統(tǒng)） in bacteria 蛋白的磷酸化及去磷酸化狀態(tài)在分解物代謝阻遏中起關鍵作用。pts系統(tǒng)是運載體家族中的轉位分子，在原核生和古細菌中廣泛存在。大腸桿菌主要通過pepsugar pts以集團轉移方式進行葡萄糖的攝取， pts包括ei，hpr，eii。前兩者為胞質可溶型蛋白，無底物識別

7、特異性。分別由psti，psth操縱子編碼，后者多為蛋白復合體，對碳水化合物具有識別特異性,可特異性識別和轉運底物分子，e.coli編碼約20種es，涉及20多種不同碳化物磷酸化轉運。hpr: histidine-containing phosphocarrier protein含組氨酸的磷酸載體蛋白 ei：extract(獲得) the phosphate from pep and adds it to the carrier protein, hpr.eii：分為eiia,eiib,eiic類別，有時eiic又會連帶上eiid磷酸轉移酶系統(tǒng)蛋白磷酸轉移酶系統(tǒng)蛋白-蛋白復合體的三維結構蛋白復

8、合體的三維結構 pts的作用過程：的作用過程： ei先從先從pep處獲得磷酸處獲得磷酸基團，并將其加載到載基團，并將其加載到載體蛋白體蛋白hpr上，然后載體上，然后載體蛋白將磷酸基團傳遞給蛋白將磷酸基團傳遞給整個系列當中相對應不整個系列當中相對應不同的轉運蛋白。磷酸基同的轉運蛋白。磷酸基團在幾種蛋白當中穿梭，團在幾種蛋白當中穿梭，從從hpr移動到移動到eiia，再到，再到eiib ，最終到達處在最終到達處在eiic（有時會帶上一個（有時會帶上一個額外的鏈額外的鏈eiid）當中的）當中的葡萄糖。每個轉運蛋白葡萄糖。每個轉運蛋白由由eii蛋白自身的各個集蛋白自身的各個集成物組成，有時會作為成物組成

9、，有時會作為隔離蛋白，有時又會在隔離蛋白，有時又會在一個長鏈蛋白質中作為一個長鏈蛋白質中作為一連串相互連結的結構一連串相互連結的結構區(qū)域區(qū)域 磷酸化的hpr是一個所有pts中eii的磷酸通用供體。這個磷酸轉移活性伴隨著從pts系列的通用磷酸轉移部分到葡萄糖特異的那條途徑。而葡萄糖特異的載體（iiaglc）這個蛋白不僅作為葡萄糖轉移過程中的中間體，同時也作為非pts通透酶和腺苷酸環(huán)化酶的調節(jié)者。hpriiaglc復合體的結構是采用同位素標記蛋白質的組合，利用多維 異核nmr光譜技術解析的。 carbohydrate transport and phosphorylation by the pts

10、 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 of which is

11、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 (in boldface

12、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 kinase. 醛糖代謝

13、pts作用機制作用機制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 same time.

14、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糖的磷酸前體物糖的磷酸前體物 primes指導指導them for entry into the energy production pathways.harvesting resources 收獲資源 the phosphotransferase system is built around a collection of spe

15、cific transporters that import resources into the cell. psi researchers have recently revealed the structure of one of these transporters, which imports a disaccharide雙糖雙糖. typical bacterial cells make many similar transporters (e. coli has at least 15) that all stand ready to import whatever sugars

16、 are available. a complex regulatory network decides which transporters are expressed and used at any given time.pst系統(tǒng)是一些特定運輸物組建的集合體，這些運輸物會向細系統(tǒng)是一些特定運輸物組建的集合體，這些運輸物會向細胞中輸入資源。胞中輸入資源。psi研究者最近發(fā)現(xiàn)了這些運輸物之一結構，研究者最近發(fā)現(xiàn)了這些運輸物之一結構，此結構是向細胞內輸入雙糖。典型的細菌細胞有許多相似的此結構是向細胞內輸入雙糖。典型的細菌細胞有許多相似的轉移物轉移物(e. coli 至少至少15），無論糖類是否

17、便于利用他們都時刻做），無論糖類是否便于利用他們都時刻做好準備向內輸入。一個好準備向內輸入。一個復雜的調控系統(tǒng)網絡決定著在特定時復雜的調控系統(tǒng)網絡決定著在特定時間中哪一種轉運物被表達或被利用。間中哪一種轉運物被表達或被利用。modular模塊化，單元化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 determined the structures of several different forms of the eiib protein from different organisms and from different sugar transport complexes.研究方法研究方法 對于包含在通過pts進行磷酸轉移的過程以及pts蛋白參與調控過程的機制的理解在很大程度上是通過蛋白組分的相互作用的種類的三維結構的可視