βVPE is involved in tapetal degradation and pollen development by activating proprotease maturation in Arabidopsis thaliana

Abstract

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