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Study on the evolution of Archaea and Bacteria from the view points of archaeal polar lipid biosynthesis

从古菌极性脂质生物合成角度研究古菌和细菌的进化

基本信息

批准号：
16580067
负责人：
KOGA Yosuke
金额：
$ 2.3万
依托单位：
University of Occupational and Environmental Health, Japan
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

项目摘要

Polar lipids are indispensable constituents of cellular membranes. Because the first cell came into existence at the occurrence of polar lipids, the elucidation of differences in the structure and biosynthetic mechanism between Archaea and Bacteria would give a clue to discuss the origin of Archaea and Bacteria, which show differences in the fundamental biochemistry. Previous studies revealed that one of the most fundamenntal biochemical differences was the stereochemical structure of glycerophosphate backbone of membrane polar lipids, and it was proposed that the segregation of the chiral lipids triggered off differentiation of the Archaea and Bacteria. The present study focused on the evolution of polar groups of membrane polar lipids in relation with the differentiation of Archaea and Bacteria.It was elucidated in the present study that synthases of inositol phospholipid and glycerol phospholipid belonged to the same enzyme family, CDP-alcohol phosphatidyltransferase family, along w … More ith serine phospholipid synthase including ester-type phospholipid synthases. This conclusion was drawn from BLAST search of archaeal and bacterial genomes using the amino acid sequence of archaetidylserine synthase as a query and in vitro studies of archaetidylserine synthase from a methanoarchaeon. Activities of monoglucosylarchaeol synthase and diglucosylarchaeol synthase were detected and partialy characterized. Saturated archaeol was sequentially glucosylated with UDP-glucose by two separate enzymes. Although glycolipid synthases in Archaea have not been phylogenetically elucidated, the outline of the enzymatic mode of reaction of archaeal glycolipid synthesis was the similar to bacterial counterparts. The archaeal monoglucosylarchaeol synthase recognized the stereostructure of the lipid substrate.It was proposed from the above results that the polar lipids of pre-cells proposed by Wachtershauser at the stage before differentiation of Archaea and Bacteria had common and contemporary polar head groups shared by Archaea and Bacteria. Polar lipids with racemic core lipid and common polar groups were segregated into homochiral polar lipids carrying common polar groups. This was the cause of differentiation of Archaea and Bacteria. Homologous enzymes for phospholipid synthesis were carried over into both domains of organisms. Stereospecific glycolipid synthases would be developed after differentiation of Archaea and Bacteria. Less

极性脂是细胞膜不可缺少的成分。由于第一个细胞是在极性脂的出现时产生的，阐明古生菌和细菌在结构和生物合成机制上的差异将为探讨古生菌和细菌的起源提供线索，因为它们在基础生物化学上表现出差异。以往的研究表明，最基本的生化差异之一是膜极性脂的甘油磷酸主链的立体化学结构，并提出手性脂的分离引发了古生菌和细菌的分化。研究了膜上极性基团的演化与古生菌和细菌分化的关系，阐明了肌醇磷脂合成酶和甘油磷脂合成酶属于同一酶家族，即CDP-醇磷脂酰基转移酶家族，与…更多的是丝氨酸磷脂合成酶，包括酯型磷脂合成酶。这一结论是以古生丝氨酸合成酶的氨基酸序列为查询，通过对古生菌和细菌基因组的BLAST搜索和对来自甲烷考古菌的古生丝氨酸合成酶的体外研究得出的。测定了单糖落叶醇合酶和二葡糖基落叶醇合酶的活性，并对其进行了部分表征。饱和的考古醇通过两种不同的酶依次与UDP-葡萄糖进行糖基化反应。虽然古生代糖脂合成酶的系统发育尚未阐明，但古生代糖脂合成的酶反应模式与细菌相似。古细菌的单糖乳糖合成酶识别脂质底物的立体结构，从以上结果推测，Wachtershauser在古生物和细菌分化前提出的前细胞的极性脂类具有古生物和细菌共有的共同和当代的极性头基。具有外消旋核心脂和共同极性基团的极性脂被分离成带有共同极性基团的同手性极性脂类。这是古生菌和细菌分化的原因。磷脂合成的同源酶被带入生物体的这两个领域。在古生菌和细菌分化后，将形成立体特异性糖脂合成酶。较少