Driouich A, Jauneau A, Staehelin L A
Centre National de la Recherche Scientifique Unité de Recherche Associée 203, Université de Rouen, Mont Saint Aignan, France.
Plant Physiol. 1997 Feb;113(2):487-92. doi: 10.1104/pp.113.2.487.
7-Dehydrobrefeldin A (7-oxo-BFA) is a brefeldin A (BFA) analog that, like BFA, is a potent phytotoxin of Alternaria carthami, a fungal pathogen of safflower (Carthamus tinctorius L.) plants. Both BFA and 7-oxo-BFA have been shown to be causal agents of the leaf spot disease of these plants. We have investigated the effects of 7-oxo-BFA on the secretion and the structure of the Golgi stacks of sycamore maple (Acer pseudoplatanus) suspension-cultured cells to determine whether 7-oxo-BFA affects these cells in the same manner as BFA. When applied at 10 micrograms/mL for 1 h, 7-oxo-BFA inhibits secretion of proteins by approximately 80%, the same value obtained for BFA. However, electron micrographs of high-pressure frozen/freeze-substituted cells demonstrated that 7-oxo-BFA is a more potent disrupter of the Golgi stacks of sycamore maple cells than BFA. In cells treated for 1 h with 10 micrograms/mL 7-oxo-BFA, very few Golgi stacks can be discerned. Most of those that are left consist of fewer than three cisternae, all of which stain like trans-Golgi cisternae. They are surrounded by clusters of large (150-300 nm in diameter), darkly staining vesicles that are embedded in a fine-filamentous, ribosome-excluding matrix. Similarly sized and stained vesicles are seen budding from the rims of the residual trans-Golgi cisternae. Both the large vesicles and the residual Golgi stack buds stain with anti-xyloglucan polysaccharide antibodies. Recovery of Golgi stacks after removal of 7-oxo-BFA from 1-h-treated cells takes 2 to 6 h, compared with 1 to 2 h for cells treated with BFA. In contrast to 7-oxo-BFA, the BFA breakdown product BFA acid had no effect either on secretion or on the secretory apparatus. This is the first report, to our knowledge of a BFA analog inhibiting secretion in a eukaryotic cell system.
7-脱氢布雷菲德菌素A（7-氧代-BFA）是布雷菲德菌素A（BFA）的类似物，与BFA一样，是红花（Carthamus tinctorius L.）植物的真菌病原体——链格孢菌的一种强效植物毒素。BFA和7-氧代-BFA均已被证明是这些植物叶斑病的病原体。我们研究了7-氧代-BFA对悬铃木（Acer pseudoplatanus）悬浮培养细胞高尔基体堆叠的分泌和结构的影响，以确定7-氧代-BFA是否以与BFA相同的方式影响这些细胞。当以10微克/毫升的浓度处理1小时时，7-氧代-BFA抑制蛋白质分泌约80%，这与BFA的抑制值相同。然而，高压冷冻/冷冻置换细胞的电子显微镜照片显示，7-氧代-BFA比BFA更能破坏悬铃木细胞的高尔基体堆叠。在用10微克/毫升7-氧代-BFA处理1小时的细胞中，几乎看不到高尔基体堆叠。剩下的大多数由少于三个扁平囊组成，所有这些扁平囊的染色都类似于反式高尔基体扁平囊。它们被大量（直径150 - 300纳米）深色染色的囊泡簇包围，这些囊泡嵌入在细丝状、不含核糖体的基质中。从残留反式高尔基体扁平囊边缘可见大小和染色相似的囊泡出芽。大囊泡和残留高尔基体堆叠芽均用抗木葡聚糖多糖抗体染色。从处理1小时的细胞中去除7-氧代-BFA后，高尔基体堆叠的恢复需要2至6小时，而用BFA处理的细胞则需要1至2小时。与7-氧代-BFA相反，BFA分解产物BFA酸对分泌或分泌装置均无影响。据我们所知，这是关于BFA类似物在真核细胞系统中抑制分泌的首次报道。
