著者

KOBAYASHI Toshihide OHTA Akinori SHIBUYA Isao

出版者

社団法人 日本生化学会

雑誌

The Journal of Biochemistry

巻号頁・発行日

vol.99, no.5, pp.1393-1400, 1986

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<i>Escherichia coli</i> mutants harboring the <i>pss-1</i> 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 <i>sn</i>-glycerol 3-phosphate on the phospholipid synthesis and the growth ability of a <i>pss-1</i> mutant. For this purpose, a pair of <i>E. coli</i> K-12 derivatives isogenic except for the <i>pss-1</i> allele was constructed from strain BB26-36 to harbor the mutations related to glycerol metabolism (<i>glpD3</i>, <i>glpR2</i>, <i>glpK</i>¹, and <i>phoA8</i>). Pulse- and uniform-labeling of phospholipids with ³²P at 42&deg;C in a synthetic medium with (0.2%) or without glycerol showed that glycerol further lowered the temperaturesensitive 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 <i>pss-1</i> mutant. The phospholipid synthesis and contents in the pssr⁺ strain were not significantly affected by glycerol. Glycerol in the medium markedly enhanced the growth defect of the <i>pss-1</i> mutant, which was remediable by sucrose. The results indicate that the intracellular pool of <i>sn</i>-glycerol 3-phosphate is the limiting factor for acidic phospholipid synthesis in the <i>pss-1</i> mutant, and cardiolipin unusually accumulated is injurious to the functional E. coif membranes. Possible determinants for the phospholipid composition of the wild-type <i>E. coli</i> cells are also discussed on the basis of the present observations.