A CDP-choline pathway for phosphatidylcholine biosynthesis in Treponema denticola.
A CDP-choline pathway for phosphatidylcholine biosynthesis in Treponema denticola.
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密螺旋体中磷脂酰胆碱生物合成的 CDP-胆碱途径。
DOI：
10.1046/j.1365-2958.2003.03839.x
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Fenno,JChristopher
中科院分区：
文献类型：
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作者：
Kent,Claudia;Gee,Patricia;Lee,SiYoung;Bian,Xuelin;Fenno,JChristopher
齿状密螺旋体和苍白密螺旋体的基因组中含有licCA基因，该基因被预测编码含有胆碱激酶和CTP（磷酸胆碱胞基转移酶）活性的融合蛋白。因为这两种生物都含有磷脂酰胆碱，这就提出了它们利用CDP -胆碱途径生物合成磷脂酰胆碱的可能性。本报告显示磷脂酰胆碱是一种主要的磷脂。Denticola，占总磷脂的35-40%。这种生物很容易将[14C]胆碱结合到磷脂酰胆碱中，表明存在依赖胆碱的生物合成途径。克隆LicCA基因，重组LicCA具有胆碱激酶和磷酸胆碱胞基转移酶活性。冰川期被打乱了。红霉素盒式诱变，产生有活力的突变体。这种破坏完全阻断了[14C]胆碱或32pi与磷脂酰胆碱的结合。另一种磷脂inT的生成速率。磷脂酰乙醇胺（denticola）在突变体中显著升高，表明这种脂质水平的升高补偿了膜中磷脂酰胆碱的损失。因此，似乎t。denticoladoes含有依赖alicCA的CDP -胆碱途径，用于磷脂酰胆碱的生物合成。
The genomes ofTreponema denticolaandTreponema pallidumcontain a gene,licCA, which is predicted to encode a fusion protein containing choline kinase and CTP:phosphocholine cytidylyltransferase activities. Because both organisms have been reported to contain phosphatidylcholine, this raises the possibility that they use a CDP‐choline pathway for the biosynthesis of phosphatidylcholine. This report shows that phosphatidylcholine is a major phospholipid inT. denticola, accounting for 35–40% of total phospholipid. This organism readily incorporated [14C]choline into phosphatidylcholine, indicating the presence of a choline‐dependent biosynthetic pathway. ThelicCAgene was cloned, and recombinant LicCA had choline kinase and CTP:phosphocholine cytidylyltransferase activity. ThelicCAgene was disrupted inT. denticolaby erythromycin cassette mutagenesis, resulting in a viable mutant. This disruption completely blocked incorporation of either [14C]choline or32Pi into phosphatidylcholine. The rate of production of another phospholipid inT. denticola, phosphatidylethanolamine, was elevated considerably in thelicCAmutant, suggesting that the elevated level of this lipid compensated for the loss of phosphatidylcholine in the membranes. Thus it appears thatT. denticoladoes contain alicCA‐dependent CDP‐choline pathway for phosphatidylcholine biosynthesis.