Rottem S, Greenberg N
Rev Infect Dis. 1982 May-Jun;4 Suppl:S99-104. doi: 10.1093/clinids/4.supplement_1.s99.
The composition and molecular organization of mycoplasmal virus L2 (MVL2) were studied and compared with those of the cell membrane of the host, Acholeplasma laidlawii strain JA1. The virus contained 0.2-0.25 mumol of polar lipids per mg of viral protein. The lipid species of the MVL2 were the same as those of the host cells. Nevertheless, the proportions between the various polar lipids were different, with a much lower content of phosphatidylglycerol in the viral lipids. Despite these quantitative differences, the fatty acid composition of MVL2 was similar to that found in the host cells, a similarly allowing alteration of the fatty acid composition and study of its effect on viral absorption, penetration, and release. Pulse-chase experiments revealed that the lipids incorporated into the virus were synthesized before and after infection. Electron paramagnetic resonance spectrometry suggested that the viral lipid domain had the properties of a lipid bilayer. Nevertheless, the hydrocarbon chains in the MVL2 envelope were less mobile than those in membranes of the host cells, a difference apparently due to the different content, composition, and disposition of proteins in the MVL2 envelope. The electrophoretic pattern of MVL2 polypeptides was dominated by four major and five minor bands distinct from the polypeptides present in A. laidlawii membranes. None of the polypeptides gave a positive periodic acid-Schiff reaction, a result suggesting the absence of glycoproteins. Selective solubilization experiments excluded the possibility that one or more of the major polypeptides was associated with a capsid structure. Lactoperoxidase-mediated iodination of intact viral particles revealed that at least two of the major polypeptides were localized on the external surface of the viral envelope. The susceptibility of these polypeptides to brief proteolytic treatment and the finding that the infectivity of the virus was dramatically affected by such treatment suggested that these polypeptides were playing a role in recognition and/or attachment of the virus to the host cells.
对支原体病毒L2（MVL2）的组成和分子结构进行了研究，并与宿主莱氏无胆甾原体JA1菌株的细胞膜进行了比较。该病毒每毫克病毒蛋白含有0.2 - 0.25微摩尔的极性脂质。MVL2的脂质种类与宿主细胞相同。然而，各种极性脂质之间的比例不同，病毒脂质中磷脂酰甘油的含量要低得多。尽管存在这些数量差异，但MVL2的脂肪酸组成与宿主细胞中的相似，同样允许改变脂肪酸组成并研究其对病毒吸附、穿透和释放的影响。脉冲追踪实验表明，掺入病毒的脂质在感染前后都有合成。电子顺磁共振光谱表明，病毒脂质结构域具有脂质双层的特性。然而，MVL2包膜中的烃链比宿主细胞膜中的烃链流动性小，这种差异显然是由于MVL2包膜中蛋白质的含量、组成和排列不同所致。MVL2多肽的电泳图谱由四条主要带和五条次要带主导，这些带与莱氏无胆甾原体膜中存在的多肽不同。没有一种多肽产生阳性过碘酸 - 希夫反应，这一结果表明不存在糖蛋白。选择性溶解实验排除了一种或多种主要多肽与衣壳结构相关的可能性。完整病毒颗粒的乳过氧化物酶介导碘化显示，至少有两种主要多肽位于病毒包膜的外表面。这些多肽对短暂蛋白酶处理的敏感性以及病毒感染性受这种处理显著影响的发现表明，这些多肽在病毒识别和/或附着于宿主细胞中起作用。
