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Alternative TitleIdentification of a membrane lipid synthesis gene in Synechocystis sp. PCC 6803
Thesis Advisor徐旭东
Degree Grantor中国科学院水生生物研究所
Place of Conferral水生生物研究所
Keyword集胞藻6803 膜脂合成 Plsx Ppete
Abstract蓝藻是地球上最早出现的能进行光合作用的原核生物。集胞藻(Synechocystis sp.)PCC6803是一种单细胞蓝藻,既可以自养生长,也可以利用葡萄糖异养生长,是蓝藻分子遗传学研究中的重要模式之一。集胞藻6803的膜系统包括外膜、质膜、类囊体膜,其膜脂的合成都是从对G3P(sn-甘油-3-磷酸)的两步脂酰化开始的。原核生物的sn-1位脂酰化反应由PlsB(即GPAT,sn-甘油-3-磷酸脂酰转移酶)或者PlsX(磷酸转移酶)和PlsY(酰基转移酶)蛋白协同催化完成,sn-2位脂酰化反应由PlsC(即LPAAT,溶血磷脂酸脂酰转移酶)催化。本研究的主要目的就是在集胞藻6803中鉴定与膜脂合成过程相关的基因,并实现对它们的调控。研究内容和结果如下: 1. 通过集胞藻6803基因组文库互补E. coli 膜脂合成突变株BB13(plsB-plsX-),筛选到了与膜脂合成有关的重要基因slr1510。slr1510与plsX相似,编码G3P sn-1位脂酰化反应中的一个磷酸转移酶。免疫印迹检测显示PlsX位于蓝藻总膜内。 2. 利用一个受铜离子调控的启动子PpetE来调控slr1510的表达。结果发现,在关闭slr1510表达的情况下,藻细胞的生长和各项生理指标受到了严重的影响,表现为:色素含量明显减少,类囊体膜结构破坏,光合放氧能力消失,呼吸作用大大降低,蛋白质发生降解。这些结果支持slr1510在膜脂合成过程起重要作用。
Other AbstractCyanobacteria are the earliest prokaryotes that perform oxygenic photosynthesis on the earth. Synechocystis sp. PCC6803, a unicellular cyanobacterium, is able to utilize light energy to grow autotrophically or glucose to grow heterotrophically. It is one of the model species used in the molecular genetics study of cyanobacteria. Biomembranes of Synechocystis 6803 include outer membranes, plasma membranes and thylakoid membranes. The synthesis of membrane lipids is initiated by two acylation reactions of G3P (sn-glycerol-3-phosphate). In prokaryotes, the acylation at sn-1 position is performed through PlsB or the PlsX/Y pathway. The first pathway is catalyzed by PlsB (GPAT, sn-glycerol-3-phosphate acyltransferase), the second pathway is coordinately catalyzed by PlsX (phosphate transferase) and PlsY (acyltransferse). The acylation at sn-2 position is catalyzed by PlsC (LPAAT, 1-acyl-glycerol-3-phosphate acyltransferase). The target of this study is to identify genes involved in the synthesis of membrane lipids in Synechocystis sp. PCC 6803 and regulate the expression of the genes. Approaches and results are summarized as follows: 1. By complementing E. coli BB13 (plsB-plsX -), a mutant defective in synthesis of membrane lipids, with a gene library of Synechocystis sp. PCC 6803, we identified slr1510 as an important gene involved in the synthesis of membrane lipids. slr1510 is similar to plsX and predicted to encode the phosphate transferase involved in the acylation at sn-1 position of G3P. Western blot detection indicated that PlsX is located in the total membranes of the cyanobacterium. 2. A copper-regulated promoter PpetE was used to regulate the expression of slr1510. When the expression of slr1510 was tuned off, the cyanobacterium no longer showed growth. In addition, pigments were significantly reduced, thylakoid membranes were destructed, oxygenic photosynthesis and respiration were greatly lowered or ceased and proteins were degraded. All these results supported that slr1510 played a key role in the synthesis of membrane lipids.
Document Type学位论文
Recommended Citation
GB/T 7714
罗泉. 集胞藻PCC6803中膜脂合成基因的鉴定[D]. 水生生物研究所. 中国科学院水生生物研究所,2007.
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