Identification and characterization of DegP, a serine protease associated with the luminal side of the thylakoid membrane
Identification and characterization of DegP, a serine protease associated with the luminal side of the thylakoid membrane
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DOI：
10.1074/jbc.273.12.7094
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发表时间：
1998-03-20
影响因子：
4.8
通讯作者：
Adam, Z
中科院分区：
文献类型：
--
作者：
Itzhaki, H;Naveh, L;Adam, Z
在类囊体腔中参与蛋白水解降解的蛋白酶在很大程度上是未知的。Western分析表明，豌豆叶绿体中含有这种蛋白酶的同源物的大肠杆菌周质丝氨酸蛋白酶DegP的抗体。这种同源物是外围绑定到类囊体膜的腔侧，只能通过高盐和非离子去污剂的组合去除。其水平增加了近a倍的豌豆幼苗暴露于高温4小时，这表明这种蛋白酶的叶绿体的热响应的作用。分离的类囊体膜含有DegP降解的β-酪蛋白（细菌蛋白酶的体外底物）的叶绿体同源物。这种活性被丝氨酸蛋白酶抑制剂部分抑制，这表明类囊体膜中的酪蛋白降解活性的至少一部分归因于DegP。叶绿体DegP的存在通过分离全长拟南芥cDNA（命名为AtDegP）得到进一步支持，该cDNA编码的蛋白质与E.大肠杆菌蛋白酶。推导的氨基酸序列的氨基末端含有一个二分转运肽，典型的蛋白质靶向类囊体腔，和蛋白质的成熟部分含有高度保守的丝氨酸蛋白酶催化三联体His-Asp-Ser. The可能的生理作用叶绿体DegP蛋白酶进行了讨论。
The proteases involved in proteolytic degradation in the thylakoid lumen are largely unknown. Western analysis with an antibody against the Escherichia coli periplasmic serine protease DegP suggested that pea chloroplasts contain a homologue of this protease. This homologue was peripherally bound to the luminal side of the thylakoid membrane and could only be removed by a combination of high salt and non-ionic detergent. Its level increased almost a-fold in pea seedlings exposed to elevated temperature for 4 h, suggesting this protease's role in the chloroplast's heat response. Isolated thylakoid membranes containing the chloroplastic homologue of DegP degraded beta-casein, an in vitro substrate of the bacterial protease. This activity was partially inhibited by a serine protease inhibitor, suggesting that at least part of the casein-degrading activity in the thylakoid membrane is attributable to DegP. The existence of chloroplastic DegP was further supported by isolating a full-length Arabidopsis cDNA (designated AtDegP) encoding a protein that is 37% identical and 60% similar to the E. coli protease. The amino terminus of the deduced amino acid sequence contained a bipartite transit peptide, typical of proteins targeted to the thylakoid lumen, and the mature portion of the protein contained the highly conserved serine protease catalytic triad His-Asp-Ser. The possible physiological roles of chloroplastic DegP protease are discussed.