Kobayashi T, Ohta A, Shibuya I
J Biochem. 1986 May;99(5):1393-400. doi: 10.1093/oxfordjournals.jbchem.a135608.
Escherichia coli mutants harboring the pss-1 allele (coding for a temperature-sensitive phosphatidylserine synthase) are temperature sensitive for growth and synthesize less phosphatidylethanolamine at higher temperatures, giving rise to abnormal membrane phospholipid compositions. To obtain information concerning the determinant for the phospholipid polar headgroup composition and the lethal factor in the defective membranes, we have examined the effect of increased supply of sn-glycerol 3-phosphate on the phospholipid synthesis and the growth ability of a pss-1 mutant. For this purpose, a pair of E. coli K-12 derivatives isogenic except for the pss-1 allele was constructed from strain BB26-36 to harbor the mutations related to glycerol metabolism (glpD3, glpR2, glpKi, and phoA8). Pulse- and uniform-labeling of phospholipids with 32P at 42 degrees C in a synthetic medium with (0.2%) or without glycerol showed that glycerol further lowered the temperature-sensitive formation of phosphatidylethanolamine, removed the phosphatidate and CDP-diacylglycerol accumulated in the absence of glycerol, and resulted in an increase in cardiolipin content in the pss-1 mutant. The phospholipid synthesis and contents in the pss+ strain were not significantly affected by glycerol. Glycerol in the medium markedly enhanced the growth defect of the pss-1 mutant, which was remediable by sucrose. The results indicate that the intracellular pool of sn-glycerol 3-phosphate is the limiting factor for acidic phospholipid synthesis in the pss-1 mutant, and cardiolipin unusually accumulated is injurious to the functional E. coli membranes. Possible determinants for the phospholipid composition of the wild-type E. coli cells are also discussed on the basis of the present observations.
携带pss - 1等位基因（编码一种温度敏感型磷脂酰丝氨酸合成酶）的大肠杆菌突变体对生长具有温度敏感性，并且在较高温度下合成的磷脂酰乙醇胺较少，导致膜磷脂组成异常。为了获取有关磷脂极性头部基团组成的决定因素以及缺陷膜中的致死因素的信息，我们研究了增加sn - 甘油3 - 磷酸供应对pss - 1突变体磷脂合成和生长能力的影响。为此，从BB26 - 36菌株构建了一对除pss - 1等位基因外其他基因均相同的大肠杆菌K - 12衍生物，使其携带与甘油代谢相关的突变（glpD3、glpR2、glpKi和phoA8）。在含有（0.2%）或不含甘油的合成培养基中于42℃用32P对磷脂进行脉冲标记和均匀标记，结果表明甘油进一步降低了磷脂酰乙醇胺的温度敏感型形成，消除了在无甘油时积累的磷脂酸和CDP - 二酰甘油，并导致pss - 1突变体中心磷脂含量增加。甘油对pss +菌株的磷脂合成和含量没有显著影响。培养基中的甘油显著加剧了pss - 1突变体的生长缺陷，而蔗糖可补救这种缺陷。结果表明，sn - 甘油3 - 磷酸的细胞内池是pss - 1突变体中酸性磷脂合成的限制因素，异常积累的心磷脂对功能性大肠杆菌膜有害。还基于当前观察结果讨论了野生型大肠杆菌细胞磷脂组成的可能决定因素。
