PROALEURAIN VACUOLAR TARGETING IS MEDIATED BY SHORT CONTIGUOUS PEPTIDE INTERACTIONS
PROALEURAIN VACUOLAR TARGETING IS MEDIATED BY SHORT CONTIGUOUS PEPTIDE INTERACTIONS
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DOI：
10.1105/tpc.4.3.307
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发表时间：
1992-03-01
期刊：
影响因子：
11.6
通讯作者：
ROGERS, JC
中科院分区：
文献类型：
--
作者：
HOLWERDA, BC;PADGETT, HS;ROGERS, JC
可溶性蛋白质靶向植物液泡是由多肽中的决定簇介导的。我们通过将来自糊粉蛋白原的不同序列整合到分泌的巯基蛋白酶原内蛋白酶B（proEP-B）中，反之亦然，鉴定了糊粉蛋白（一种植物液泡巯基蛋白酶）的液泡靶向决定簇。通过在电穿孔的烟草原生质体中瞬时表达来分析嵌合蛋白的靶向命运。靶向决定簇SSSSFADSNPIR位于糊粉蛋白前肽的N末端，并且其取代成EP-B的前肽引起所得嵌合蛋白的空泡靶向。该决定子可以分为两个较小的决定子，SSSSFADS和SNPIR，每个都足以将proEP-B嵌合体靶向液泡，但效率较低。这些较小的决定因素以积极的方式相互作用，因为组合的决定因素SSSSFADSNPIR靶向proEP-B的效率大于单独的每个较小的决定因素。因此，当任一较小的决定簇通过用类似定位的proEP-B序列替换而被破坏时，糊粉蛋白靶向的效率降低。对前糊粉蛋白的进一步实验确定了与SSSSFADSNPIR决定簇相邻的另一个决定簇VTDRAAST，该决定簇对于有效的液泡靶向也是必要的。我们的研究结果提供的证据表明，有效的液泡靶向这种巯基蛋白酶在植物细胞中介导的较小的连续决定簇的联合作用，其中两个单独的是足够的液泡靶向。
Targeting of soluble proteins to the plant vacuole is mediated by determinants that reside in the polypeptide. We identified the vacuolar targeting determinant of aleurain, a plant vacuolar thiol protease, by incorporating different sequences from proaleurain into the secreted thiol protease, proendoproteinase B (proEP-B), and vice versa. The targeting fates of the chimeric proteins were analyzed by transient expression in electroporated tobacco protoplasts. The targeting determinant SSSSFADSNPIR is positioned at the N terminus of the aleurain propeptide, and its substitution into the propeptide of EP-B caused vacuolar targeting of the resulting chimeric protein. This determinant can be divided into two smaller determinants, SSSSFADS and SNPIR, each of which is sufficient to target proEP-B chimeras to the vacuole, but with lower efficiency. These smaller determinants interact in a positive manner because the combined determinant SSSSFADSNPIR targeted proEP-B with an efficiency greater than each of the smaller determinants alone. Accordingly, the efficiency of aleurain targeting was decreased when either of the smaller determinants was disrupted by replacement with similarly positioned proEP-B sequences. Further experiments on proaleurain identified an additional determinant, VTDRAAST, adjacent to the SSSSFADSNPIR determinant that is also necessary for efficient vacuolar targeting. Our results provide evidence that efficient vacuolar targeting of this thiol protease in plant cells is mediated by the combined action of smaller contiguous determinants; two of these alone are sufficient for vacuolar targeting.