Huang Ying-Ping, Hou Pei-Yu, Chen I-Hsuan, Hsu Yau-Huei, Tsai Ching-Hsiu, Cheng Chi-Ping
Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan.
Department of Life Sciences, Tzu Chi University, Hualien, Taiwan.
J Exp Bot. 2020 Dec 31;71(22):6932-6944. doi: 10.1093/jxb/eraa422.
NbRabF1, a small GTPase from Nicotiana benthamiana and a homolog of Arabidopsis thaliana Ara6, plays a key role in regulating Bamboo mosaic virus (BaMV) movement by vesicle transport between endosomal membranes. Reducing the expression of NbRabF1 in N. benthamiana by virus-induced gene silencing decreased the accumulation of BaMV, and with smaller infection foci on inoculated leaves, but had no effect in protoplasts. Furthermore, transient expression of NbRabF1 increased the accumulation of BaMV in inoculated leaves. Thus, NbRabF1 may be involved in the cell-to-cell movement of BaMV. The potential acyl modification sites at the second and third amino acid positions of NbRabF1 were crucial for membrane targeting and BaMV accumulation. The localization of mutant forms of NbRabF1 with the GDP-bound (donor site) and GTP-bound (acceptor site) suggested that NbRabF1 might regulate vesicle trafficking between the Golgi apparatus and plasma membrane. Furthermore, GTPase activity could also be involved in BaMV cell-to-cell movement. Overall, in this study, we identified a small GTPase, NbRabF1, from N. benthamiana that interacts with its activation protein NbRabGAP1 and regulates vesicle transport from the Golgi apparatus to the plasma membrane. We suggest that the BaMV movement complex might move from cell to cell through this vesicle trafficking route.
NbRabF1是一种来自本氏烟草的小GTP酶，是拟南芥Ara6的同源物，通过内体膜之间的囊泡运输在调节竹花叶病毒（BaMV）移动中起关键作用。通过病毒诱导的基因沉默降低本氏烟草中NbRabF1的表达，会减少BaMV的积累，接种叶片上的感染病灶也更小，但在原生质体中没有影响。此外，NbRabF1的瞬时表达增加了接种叶片中BaMV的积累。因此，NbRabF1可能参与BaMV的细胞间移动。NbRabF1第二和第三个氨基酸位置的潜在酰基修饰位点对于膜靶向和BaMV积累至关重要。具有结合GDP（供体位点）和结合GTP（受体位点）的NbRabF1突变体形式的定位表明，NbRabF1可能调节高尔基体和质膜之间的囊泡运输。此外，GTP酶活性也可能参与BaMV的细胞间移动。总体而言，在本研究中，我们从本氏烟草中鉴定出一种小GTP酶NbRabF1，它与其激活蛋白NbRabGAP1相互作用，并调节从高尔基体到质膜的囊泡运输。我们认为BaMV移动复合体可能通过这条囊泡运输途径在细胞间移动。
