Ikuta K, Luftig R B
Virology. 1986 Oct 15;154(1):195-206. doi: 10.1016/0042-6822(86)90441-1.
Cerulenin, an inhibitor of de novo fatty acid (and cholesterol) biosynthesis, has been shown to significantly decrease (greater than 75%) the amount of Moloney murine leukemia virus (MMuLV) released into the culture medium of chronically infected mouse fibroblasts (I. Katoh, Y. Yoshinaka, and R.B. Luftig, 1986, Virus Res., in press). In order to clarify the mechanism by which this decrease in virus production occurs, we analyzed the kinetics of gag and env coded protein synthesis in M-MuLV infected, cerulenin-treated cells by immunoprecipitation with monospecific antisera to p30, p12, p10, gp70, and p15(E). We found that in pulse (15 min-2 hr)-chase (0-4 hr) experiments the cleavage of not only Pr65gag to p30 and other gag coded proteins but Pr80env to gp70 and Pr15(E) as well, was greatly reduced by cerulenin treatment. Further, since the total amount of label in the Pr65gag and Pr80env bands remained about the same or was slightly decreased in 2-hr pulsed, cerulenin-treated cells, this suggests that cerulenin decreases virus production, in part, by inhibiting the cleavage of both precursor gag and env coded polyproteins during virus assembly and budding at the cell membrane. We also observed that at longer chase periods (4 hr), the effect of cerulenin could be partially overriden in that minor amounts of cleaved gag and env coded polyproteins were produced and assembled into virion particles. However, these particles contained abnormally large amounts of the uncleaved precursor Pr65gag, suggesting that maturation was incomplete. The above results suggest two independent, but not exclusive, possible mechanisms of cerulenin action to block M-MuLV production, viz. cerulenin decreases the pool of fatty acids, thereby inhibiting fatty acid acylation of Pr65gag, as well as Pr80env, and thus preventing the interaction between gag (the p15 antigenic determinant on Pr65gag) and env [the p15(E) antigenic determinant of Pr15(E)] coded gene products at the cell membrane needed for efficient virus assembly (M. Satake and R. B. Luftig, 1983, Virology 124, 259-273), and cerulenin inhibits one or more proteolytic enzymes responsible for the cleavage of Pr65gag and Pr80env.
浅蓝菌素是一种从头合成脂肪酸（和胆固醇）的抑制剂，已被证明能显著降低（超过75%）释放到慢性感染小鼠成纤维细胞培养基中的莫洛尼氏鼠白血病病毒（MMuLV）的量（I. 加藤、Y. 吉中、R.B. 卢夫蒂格，1986年，《病毒研究》，即将发表）。为了阐明病毒产生量下降的机制，我们通过用针对p30、p12、p10、gp70和p15（E）的单特异性抗血清进行免疫沉淀，分析了在感染M-MuLV且经浅蓝菌素处理的细胞中gag和env编码蛋白合成的动力学。我们发现，在脉冲（15分钟至2小时）-追踪（0至4小时）实验中，浅蓝菌素处理极大地减少了不仅是Pr65gag裂解为p30和其他gag编码蛋白，还有Pr80env裂解为gp70和Pr15（E）的过程。此外，由于在经浅蓝菌素处理的细胞中，2小时脉冲后Pr65gag和Pr80env条带中的总标记量保持大致相同或略有下降，这表明浅蓝菌素部分通过抑制病毒装配和细胞膜出芽过程中前体gag和env编码多蛋白的裂解来降低病毒产生量。我们还观察到，在更长的追踪期（4小时），浅蓝菌素的作用可被部分克服，因为产生了少量裂解的gag和env编码多蛋白并组装成病毒粒子。然而，这些粒子含有异常大量未裂解的前体Pr65gag，表明成熟不完全。上述结果提示了浅蓝菌素阻断M-MuLV产生的两种独立但并非相互排斥的可能机制，即浅蓝菌素减少脂肪酸池，从而抑制Pr65gag以及Pr80env的脂肪酸酰化，进而阻止gag（Pr65gag上的p15抗原决定簇）和env [Pr15（E）的p15（E）抗原决定簇]编码基因产物在细胞膜上高效病毒装配所需的相互作用（M. 佐竹和R.B. 卢夫蒂格，1983年，《病毒学》124卷，259 - 273页），以及浅蓝菌素抑制一种或多种负责Pr65gag和Pr80env裂解的蛋白水解酶。
