Macreadie I G, Thorburn D R, Kirby D M, Castelli L A, de Rozario N L, Azad A A
Biomolecular Research Institute, Parkville, Victoria, Australia.
FEBS Lett. 1997 Jun 30;410(2-3):145-9. doi: 10.1016/s0014-5793(97)00542-5.
The biological effects of the HIV-1 accessory protein, Vpr, have been studied in yeast expression systems. In our previous study [1], employing the pCUP1-vpr copper-inducible expression cassette, Vpr was shown to cause growth arrest and structural defects. In this study yeast constitutively expressing vpr, through elevated copy number and/or elevated transcription levels, displayed no growth arrest in fermentative growth conditions while Vpr was produced at much lower levels than in the inducible expression system. However, such cells were respiratory deficient and unable to utilise ethanol or glycerol as the sole carbon source. They exhibited gross mitochondrial dysfunction displayed in the loss of respiratory chain complex I, II, III, IV and citrate synthase activities. The effects on mitochondria required a C-terminal domain of Vpr that contains a conserved amino acid sequence motif HFRIGCRHSRIG. These results suggest that the widely observed phenomenon of 'Vpr-induced growth arrest' in human cells could be due to mitochondrial dysfunction.
HIV-1辅助蛋白Vpr的生物学效应已在酵母表达系统中进行了研究。在我们之前的研究[1]中，使用pCUP1-vpr铜诱导表达盒，Vpr被证明会导致生长停滞和结构缺陷。在本研究中，通过增加拷贝数和/或提高转录水平组成型表达vpr的酵母，在发酵生长条件下未出现生长停滞，而Vpr的产生水平比诱导表达系统中低得多。然而，这些细胞呼吸功能缺陷，无法利用乙醇或甘油作为唯一碳源。它们表现出严重的线粒体功能障碍，表现为呼吸链复合体I、II、III、IV和柠檬酸合酶活性丧失。对线粒体的影响需要Vpr的C末端结构域，该结构域包含保守的氨基酸序列基序HFRIGCRHSRIG。这些结果表明，在人类细胞中广泛观察到的“Vpr诱导的生长停滞”现象可能是由于线粒体功能障碍。
