细菌的磷酸转移酶系统是.ppt

细菌的磷酸转移酶系统; 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 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. ;细菌中糖的磷酸转移酶功能发现;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状态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。大肠杆菌主要通过PEP—sugar PTS以集团转移方式进行葡萄糖的摄取， 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pstI，pstH操纵子编码，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EⅡs，涉及20多种不同碳化物磷酸化转运。;Hpr: histidine-containing phosphocarrier protein含组氨酸的磷酸载体蛋白 EI：extract(获得) the phosphate from PEP and adds it to the carrier protein, HPr. EII：分为EIIA,EIIB,EIIC类别，有时EIIC又会连带上EIID;PTS的作用过程： EI先从PEP处获得磷酸基团，并将其加载到载体蛋白HPr上，然后载体蛋白将磷酸基团传递给整个系列当中相对应不同的转运蛋白。磷酸基团在几种蛋白当中穿梭，从HPr移动到EIIA，再到EIIB ，最终到达处在EIIC（有时会带上一个额外的链EIID）当中的葡萄糖。每个转运蛋白由EII蛋白自身的各个集成物组成，有时会作为隔离蛋白，有时又会在一个长链蛋白质中作为一连串相互连结的结构区域;磷酸化的HPr是一个所有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节者。HPr—IIAGlc复合体的结构是采用同位素标记蛋白质的组合，利用多维 异核NMR光谱技术解析的。 ;Carbohydrate transport and phosphorylation 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 of 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 i