Sequence and inactivation of the pss gene of Escherichia coli. Phosphatidylethanolamine may not be essential for cell viability.
Sequence and inactivation of the pss gene of Escherichia coli. Phosphatidylethanolamine may not be essential for cell viability.
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DOI：
10.1016/s0021-9258(18)99281-1
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
A. DeChavigny;P. Heacock;W. Dowhan
中科院分区：
文献类型：
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作者：
A. DeChavigny;P. Heacock;W. Dowhan
磷脂酰乙醇胺是大肠杆菌中唯一的两性离子磷脂，占该生物总甘油磷脂的70-80%。为了研究磷脂酰乙醇胺在大肠杆菌中的功能，我们构建了编码磷脂酰丝氨酸合成酶基因的失活等位基因（pss93::kan），该基因催化了磷脂酰乙醇胺合成的承诺步骤。该突变体的生长依赖于野生型基因的质粒拷贝。野生型基因突变体固化后，当磷脂酰乙醇胺含量达到总磷脂的30%时，生长停止。二价金属离子在毫摩尔浓度下抑制突变体生长表型的效率顺序如下：Ca2+大于Mg2+大于Sr2+。虽然没有检测到磷脂酰丝氨酸合成酶活性，但在含有20 mM Mg2+的富培养基中生长多代后，磷脂酰乙醇胺仍占总磷脂的0.007%。其余的磷脂主要是磷脂酰甘油和心磷脂，没有其他独特的含磷酸氯仿可溶性物质存在。磷脂蛋白比和脂肪酸组成与亲本菌株非常相似。由于缺乏磷脂酰乙醇胺而导致的宽二价金属离子缺陷，表明该磷脂在大肠杆菌中的主要结构作用。
Phosphatidylethanolamine is the only zwitterionic phospholipid in Escherichia coli and accounts for 70-80% of the total glycerophospholipids of this organism. To investigate the function of phosphatidylethanolamine in E. coli, we constructed an inactivated allele (pss93::kan) of the gene encoding the phosphatidylserine synthase which catalyzes the committed step to the synthesis of phosphatidylethanolamine. Growth of this mutant was dependent on a plasmid-borne copy of the wild type gene. After curing the mutant of the wild type gene, growth stopped when the content of phosphatidylethanolamine reached 30% of the total phospholipid. Divalent metal ions at millimolar concentrations suppressed the growth phenotype of the mutant in the following order of efficiency: Ca2+ greater than Mg2+ greater than Sr2+. Although phosphatidylserine synthase activity was not detectable, phosphatidylethanolamine was still present at 0.007% of the total phospholipid after growth for many generations in rich medium containing 20 mM Mg2+. The remainder of the phospholipid was primarily phosphatidylglycerol and cardiolipin with no other unique phosphate-containing chloroform-soluble material present. The phospholipid to protein ratio and the fatty acid composition were very similar to the parental strain. The broad divalent metal ion auxotrophy brought about by the lack of phosphatidylethanolamine suggests a primarily structural role for this phospholipid in E. coli.