Reichel C, Beachy R N
Division of Plant Biology, BCC 206, Department of Cell Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
Proc Natl Acad Sci U S A. 1998 Sep 15;95(19):11169-74. doi: 10.1073/pnas.95.19.11169.
The tobacco mosaic virus (TMV) movement protein (MP) facilitates transport of virus infection between adjacent cells by modifying plasmodesmata. Previous studies suggested that the cytoskeleton and the endomembrane system are involved in this transport. We examined the effects of TMV infection on the endoplasmic reticulum (ER) in transgenic Nicotiana benthamiana that accumulate the green fluorescent protein (GFP) in the ER. Fluorescence microscopy was used to show that early in infection the ER undergoes dramatic morphological changes that include the conversion of tubular ER into large aggregates that revert to tubular ER in later stages of infection. These changes parallel MP accumulation and degradation. Furthermore, a fusion protein comprising MP fused to GFP accumulates in or on these large aggregates of ER. Expression of MP-GFP in the absence of virus infection led to the production of fluorescent aggregates of the same apparent form and size. Microsomes isolated from infected leaves contain MP. We show that the MP appears to behave as an integral ER membrane protein and is exposed on the cytosolic face of the ER. The importance of the association of MP with ER and its possible role in intracellular and intercellular spread of infection is discussed.
烟草花叶病毒（TMV）运动蛋白（MP）通过修饰胞间连丝促进病毒感染在相邻细胞间的传播。先前的研究表明，细胞骨架和内膜系统参与了这种传播过程。我们检测了TMV感染对转基因本氏烟草内质网（ER）的影响，该转基因烟草在内质网中积累绿色荧光蛋白（GFP）。荧光显微镜观察显示，在感染早期内质网会发生显著的形态变化，包括管状内质网转变为大的聚集体，而在感染后期又恢复为管状内质网。这些变化与MP的积累和降解过程同步。此外，一种由MP与GFP融合而成的融合蛋白在这些内质网大聚集体中或其表面积累。在无病毒感染情况下表达MP-GFP会导致产生相同表观形态和大小的荧光聚集体。从感染叶片中分离得到的微粒体含有MP。我们发现MP似乎表现为一种内质网整合膜蛋白，且暴露在内质网的胞质面上。本文讨论了MP与内质网结合的重要性及其在细胞内和细胞间感染传播中可能发挥的作用。
