PROPEPTIDE OF A PRECURSOR TO A PLANT VACUOLAR PROTEIN REQUIRED FOR VACUOLAR TARGETING
PROPEPTIDE OF A PRECURSOR TO A PLANT VACUOLAR PROTEIN REQUIRED FOR VACUOLAR TARGETING
复制标题
DOI：
10.1073/pnas.88.3.834
复制
发表时间：
1991-02-01
影响因子：
11.1
通讯作者：
NAKAMURA, K
中科院分区：
文献类型：
--
作者：
MATSUOKA, K;NAKAMURA, K
孢子素是一种不含聚糖的蛋白质，在甘薯块根的液泡中大量积累。 它被合成为具有由21个氨基酸的信号肽和16个氨基酸的前肽组成的N-末端延伸的前体前体。 从孢子素的cDNA克隆中删除了总共48个碱基对，对应于编码前肽的核苷酸序列。 将该DELTA-pro突变体序列以及野生型孢子素cDNA序列置于花椰菜花叶病毒35 S转录物启动子的下游，并通过农杆菌介导的转化引入悬浮培养的烟草细胞的基因组中。 与表达野生型前体的细胞中孢子素的空泡定位相反，孢子素从表达DELTA-pro前体的细胞分泌到培养基中。 的分泌形式的孢子素是较短的两个氨基酸在其N末端比正宗的孢子素;它迁移在SDS/聚丙烯酰胺凝胶电泳过程中，由于分子内二硫键的存在，正宗的孢子素。 孢子素从细胞中分泌的动力学与宿主烟草细胞正常分泌的蛋白质的动力学相似。 这些结果表明，孢子素的前体的前肽是正确靶向孢子素的液泡所需的，并且蛋白质可以在不存在功能性分选信号的情况下通过整体流动默认途径从植物细胞分泌。
Sporamin is a protein without glycans that accumulates in large quantities in the vacuoles of the tuberous root of the sweet potato. It is synthesized as a prepro precursor with an N-terminal extension composed of a 21-amino-acid signal peptide and a 16-amino-acid propeptide. A total of 48 base pairs, corresponding to the nucleotide sequence that encodes the propeptide, was deleted from a cDNA clone for sporamin. This DELTA-pro mutant sequence, as well as the sequence of the wild-type sporamin cDNA, was placed downstream from the promoter of the 35S transcript from cauliflower mosaic virus and introduced into the genome of suspension-cultured tobacco cells by Agro-bacterium-mediated transformation. In contrast to the vacuolar localization of sporamin in cells that expressed the wild-type precursor, sporamin was secreted into the culture medium from cells in which the DELTA-pro precursor was expressed. The secreted form of sporamin was shorter by two amino acids at its N terminus than authentic sporamin; it migrated anomalously during electrophoresis on SDS/polyacrylamide gel as a result of the presence of intramolecular disulfide bridges, as does authentic sporamin. The kinetics of secretion of sporamin from the cell were similar to those of proteins normally secreted by the host tobacco cells. These results indicate that the propeptide of the precursor to sporamin is required for correct targeting of sporamin to the vacuole and that proteins can be secreted from plant cells by a bulk-flow default pathway in the absence of a functional sorting signal.