Membrane lipids are essential participants in cellular events, but only a small number of lipid-interacting proteins have been characterized. Taking advantage of the small genome (~270 genes) of the vaccinia virus, we screened for soluble lipid-binding proteins and found 27 proteins to be soluble after expression in Escherichia coli. Among them, 4 proteins were found to strongly bind to the total bovine brain lipid extract (Folch I fraction) that contained large amounts of phosphatidylserine in vitro. Out of the 4 proteins, 3 were unique proteins to viruses. Another protein, K1, solely contained an ankyrin repeat domain (ARD). ARD is conserved in large numbers of proteins in bacteria, archaea, eukaryotes and viruses, suggesting the possibilities of the membrane binding of ARDs in varieties of proteins. Furthermore, K1 deformed the lipid membrane dependently on the charged lipids. The tubulation and membrane binding was enhanced with increased negative membrane charge from phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2 ). The basic amino acid residues in the ARD were essential for membrane deformation, suggesting electrostatic interactions between K1 and the membrane for membrane deformation.

中文翻译：

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牛痘病毒K1锚蛋白重复域蛋白的膜结合和变形特性。

膜脂质是细胞事件中必不可少的参与者，但只有少数脂质相互作用蛋白得到了表征。利用牛痘病毒的小基因组（约270个基因），我们筛选了可溶性脂质结合蛋白，发现27种蛋白在大肠杆菌中表达后可溶。其中，有4种蛋白质与体外含有大量磷脂酰丝氨酸的牛脑总脂质提取物（Folch I馏分）牢固结合。在这4种蛋白质中，有3种是病毒的独特蛋白质。另一种蛋白质K1仅包含锚蛋白重复域（ARD）。ARD在细菌，古细菌，真核生物和病毒中的大量蛋白质中均被保守，这提示ARDs与多种蛋白质膜结合的可能性。此外，K1依赖于带电的脂质使脂质膜变形。磷脂酰肌醇4,5-二磷酸酯（PI（4,5）P2）的负膜电荷增加，从而增强了输卵管和膜的结合。ARD中的碱性氨基酸残基对于膜变形是必不可少的，表明K1和膜之间的静电相互作用对于膜变形。