MOLECULAR CHARACTERIZATION OF A VACUOLAR PROCESSING ENZYME RELATED TO A PUTATIVE CYSTEINE PROTEINASE OF SCHISTOSOMA-MANSONI
MOLECULAR CHARACTERIZATION OF A VACUOLAR PROCESSING ENZYME RELATED TO A PUTATIVE CYSTEINE PROTEINASE OF SCHISTOSOMA-MANSONI
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DOI：
10.1105/tpc.5.11.1651
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发表时间：
1993-11-01
期刊：
影响因子：
11.6
通讯作者：
NISHIMURA, M
中科院分区：
文献类型：
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作者：
HARANISHIMURA, I;TAKEUCHI, Y;NISHIMURA, M
各种液泡蛋白的前蛋白通过独特的液泡加工酶的作用被翻译后加工成成熟形式。如果这样的加工酶与前蛋白底物一起被运输到液泡中，则该酶必须是潜伏形式。液泡加工酶，37-kD半胱氨酸蛋白酶，在成熟的蓖麻种子胚乳的免疫细胞化学定位的地方在液泡基质中的酶，在那里也存在各种前蛋白。为了表征液泡加工酶的分子结构，我们分离了该酶的cDNA。推导的一级结构的55 kD前体是33%相同的假定半胱氨酸蛋白酶的人类寄生虫曼氏血吸虫。前体由信号肽、37-kD活性加工酶结构域和前肽片段组成。虽然在大肠杆菌中表达的前体没有液泡加工活性，但在大肠杆菌中表达的36-kD免疫阳性蛋白。大肠杆菌是活性的。这些结果表明，液泡加工酶的激活需要前体的14 kD C-末端前肽片段的蛋白水解裂解。
Proproteins of various vacuolar proteins are post-translationally processed into mature forms by the action of a unique vacuolar processing enzyme. If such a processing enzyme is transported to vacuoles together with proprotein substrates, the enzyme must be a latent form. Immunocytochemical localization of a vacuolar processing enzyme, a 37-kD cysteine proteinase, in the endosperm of maturing castor bean seeds places the enzyme in the vacuolar matrix, where a variety of proproteins is also present. To characterize a molecular structure of vacuolar processing enzyme, we isolated a cDNA for the enzyme. Deduced primary structure of a 55-kD precursor is 33% identical to a putative cysteine proteinase of the human parasite Schistosoma mansoni. The precursor is composed of a signal peptide, a 37-kD active processing enzyme domain, and a propeptide fragment. Although the precursor expressed in Escherichia coli has no vacuolar processing activity, a 36-kD immunopositive protein expressed in E. coli is active. These results suggest that the activation of the vacuolar processing enzyme requires proteolytic cleavage of a 14-kD C-terminal propeptide fragment of the precursor.