Archaea-type ether lipids in Bacteria: biosynthesis, processing, and physiological function

醚脂质组成的sn-甘油-1-磷酸（G1 P）的支架与连接聚异戊二烯侧链已被发现专门内的degenea，因此被认为是这个系统发育域的标志。我们最近已经证明了这个范例是不成立的，通过显示聚异戊二烯甘油磷酸合酶PcrB催化合成的G1 P为基础的醚脂质heptaprenylglyceryl phosphate（HepGP）在枯草芽孢杆菌和相关的革兰氏阳性菌从域细菌。我们进一步证明HepGP在体内通过去磷酸化和乙酰化进行加工。由于这种修改以前没有观察到任何醚脂质，我们将纯化和表征所涉及的磷酸酶和乙酰转移酶。此外，我们计划通过分析各种B的生长表型和膜组成来阐明新型细菌醚脂的生物学功能。枯草杆菌敲除菌株与野生型细胞相比。在数据库搜索中，我们已经确定了细菌中的第二组聚异戊二烯甘油磷酸脱氢酶，其仅在革兰氏阴性菌中发现，并且其序列与PcrB显著不同。我们将确定的聚异戊二烯基底物和醚脂产品的这一未表征的组的酶和阐明的结构基础的底物特异性的聚异戊二烯甘油磷酸脱氢酶从细菌相比，那些的pestreea。 我们的研究将提供一个全面的了解醚脂的生物合成和生理功能的细菌。

Ether lipids consisting of a sn-glycerol-1-phosphate (G1P) scaffold with attached polyprenyl side chains have been found exclusively within the Archaea and have therefore been considered a hallmark of this phylogenetic domain. We have recently disproved this paradigm by showing that the polyprenylglyceryl phosphate synthase PcrB catalyzes the synthesis of the G1P-based ether lipid heptaprenylglyceryl phosphate (HepGP) in Bacillus subtilis and related Gram-positive species from the domain Bacteria. We have further demonstrated that HepGP is processed in vivo by dephosphorylation and acetylation. Since such modifications have previously not been observed for any ether lipid, we will purify and characterize the involved phosphatase and acetyltransferase enzymes. Moreover, we plan to elucidate the biological function of the novel bacterial ether lipids by analyzing the growth phenotype and membrane composition of various B. subtilis knock-out strains in comparison with wild-type cells. In a database search we have identified a second group of polyprenylglyceryl phosphate synthases in Bacteria, which are found exclusively in Gram-negative species and whose sequences differ considerably from PcrB. We will identify the polyprenyl substrate and the ether lipid product of this uncharacterized group of enzymes and elucidate the structural basis for the substrate specificities of polyprenylglyceryl phosphate synthases from Bacteria in comparison to those of Archaea. Our studies shall provide a comprehensive understanding of the biosynthesis and physiological function of ether lipids in Bacteria.