Vacuolar processing enzyme (VPE) is responsible for the maturation and activation of vacuolar proteins in plants. We found that βVPE was involved in tapetal degradation and pollen development by transforming proproteases into mature protease in Arabidopsis thaliana. βVPE was expressed specifically in the tapetum from stages 5-8 of anther development. The βVPE protein first appeared as a proenzyme and transformed into the mature enzyme before stages 7-8. The recombinant βVPE protein self-cleaved and transformed to a 27-kD mature protein at pH 5.2. The mature βVPE protein could induce the maturation of CEP1 in vitro. βvpe mutants exhibited delayed vacuolar degradation and decreased pollen fertility. The maturation of CEP1, RD19A, and RD19C were seriously inhibited in βvpe mutants. Our results indicate that βVPE is a crucial processing enzyme that directly participates in the maturation of cysteine proteases before vacuolar degradation, and is indirectly involved in pollen development and tapetal cell degradation.

中文翻译：

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βVPE 通过激活拟南芥中的蛋白酶成熟参与绒毡层降解和花粉发育。

液泡加工酶 (VPE) 负责植物中液泡蛋白的成熟和活化。我们发现βVPE通过将原蛋白酶转化为拟南芥中的成熟蛋白酶而参与绒毡层降解和花粉发育。βVPE 在花药发育 5-8 阶段的绒毡层中特异性表达。βVPE 蛋白首先以酶原形式出现，并在第 7-8 阶段之前转化为成熟酶。重组 βVPE 蛋白在 pH 5.2 下自我切割并转化为 27-kD 成熟蛋白。成熟的βVPE蛋白可以在体外诱导CEP1的成熟。βvpe 突变体表现出液泡降解延迟和花粉生育力下降。CEP1、RD19A和RD19C的成熟在βvpe突变体中受到严重抑制。