Structural and mechanistic insights into the biosynthesis of CDP-archaeol in membranes.
Structural and mechanistic insights into the biosynthesis of CDP-archaeol in membranes.
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对膜中 CDP-古菌醇生物合成的结构和机制的见解。
DOI：
10.1038/cr.2017.122
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发表时间：
2017
期刊：
影响因子：
44.1
通讯作者：
Cheng Wei
中科院分区：
文献类型：
--
作者：
Ren Sixue;Caforio Antonella;Yang Qin;Sun Bo;Yu Feng;Zhu Xiaofeng;Wang Jinjing;Dou Chao;Fu Qiuyu;Huang Niu;Sun Qiu;Nie Chunlai;Qi Shiqian;Gong Xinqi;He Jianhua;Wei Yuquan;Driessen Arnold Jm;Cheng Wei
古生菌、细菌和真核生物的分化是进化的基本步骤。这一事件的一个标志是这些王国之间膜脂化学的主要差异。细菌和真核生物的膜主要由与甘油-3-磷酸酯键合的直链脂肪酸组成，而古细菌磷脂由与甘油-1-磷酸酯键合的类异戊二烯链组成。值得注意的是，这些脂质的生物合成的机制仍然难以捉摸。在这里，我们报告的CDP-古醇合酶（汽车）的Aeropyrum pernix（ApCarS）的结构在CTP和Mg 2+结合状态下的分辨率为2.4 μ m。该酶包含具有五个螺旋和细胞质环的跨膜结构域，其一起形成提供CTP结合位点的大的带电腔。CTP和Mg 2+的结合位置的鉴定使特异性亲脂性底物结合位点的建模成为可能，这得到了定点诱变、底物结合亲和力分析和酶测定的支持。我们建议，古菌结合在两个疏水膜嵌入的凹槽形成的灵活的跨膜螺旋5（TM 5），连同TM 1和TM 4。总的来说，结构的比较和分析，结合功能的研究，不仅阐明了机制的管理与醚键合的类异戊二烯链的磷脂的生物合成的CTP转移酶，但也提供了洞察这个酶超家族从古细菌到细菌和真核生物的进化。
The divergence of archaea, bacteria and eukaryotes was a fundamental step in evolution. One marker of this event is a major difference in membrane lipid chemistry between these kingdoms. Whereas the membranes of bacteria and eukaryotes primarily consist of straight fatty acids ester-bonded to glycerol-3-phosphate, archaeal phospholipids consist of isoprenoid chains ether-bonded to glycerol-1-phosphate. Notably, the mechanisms underlying the biosynthesis of these lipids remain elusive. Here, we report the structure of the CDP-archaeol synthase (CarS) of Aeropyrum pernix (ApCarS) in the CTP-and Mg 2+-bound state at a resolution of 2.4 Å. The enzyme comprises a transmembrane domain with five helices and cytoplasmic loops that together form a large charged cavity providing a binding site for CTP. Identification of the binding location of CTP and Mg 2+ enabled modeling of the specific lipophilic substrate-binding site, which was supported by site-directed mutagenesis, substrate-binding affinity analyses, and enzyme assays. We propose that archaeol binds within two hydrophobic membrane-embedded grooves formed by the flexible transmembrane helix 5 (TM5), together with TM1 and TM4. Collectively, structural comparisons and analyses, combined with functional studies, not only elucidated the mechanism governing the biosynthesis of phospholipids with ether-bonded isoprenoid chains by CTP transferase, but also provided insights into the evolution of this enzyme superfamily from archaea to bacteria and eukaryotes.