A novel plant protein-disulfide isomerase involved in the oxidative folding of cystine knot defense proteins
A novel plant protein-disulfide isomerase involved in the oxidative folding of cystine knot defense proteins
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DOI：
10.1074/jbc.m700018200
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发表时间：
2007-07-13
影响因子：
4.8
通讯作者：
Craik, David J.
中科院分区：
文献类型：
--
作者：
Gruber, Christian W.;Cemazar, Masa;Craik, David J.
我们已经从咖啡科植物Oldenlandia affinis（OaPDI）中分离出一种蛋白质二硫键异构酶（PDI），这种植物积累称为环肽的打结环状蛋白。新的植物PDI似乎参与环肽的生物合成，因为它共表达并与环肽前体蛋白Oak 1相互作用。OaPDI表现出类似的异构酶活性，但比人PDI更大的伴侣活性。由于预测OaPDI的结构域c具有中性pI，我们得出结论，该结构域不一定是酸性的，PDI是功能性伴侣。其-157 +/-4 mV的氧化还原电位支持其作为植物中的功能性氧化还原酶的作用。通过比较在OaPDI存在和不存在下kalata B1衍生物的折叠，研究了植物环肽的酶辅助折叠机制。OaPDI显着提高了正确的氧化折叠的kalata B1在生理pH值。折叠中间体的详细调查表明，二硫键异构化是一个重要的作用，新的植物PDI，是一个重要的步骤，在生产杀虫环肽。
We have isolated a protein-disulfide isomerase (PDI) from Oldenlandia affinis (OaPDI), a coffee family ( Rubiaceae) plant that accumulates knotted circular proteins called cyclotides. The novel plant PDI appears to be involved in the biosynthesis of cyclotides, since it co-expresses and interacts with the cyclotide precursor protein Oak1. OaPDI exhibits similar isomerase activity but greater chaperone activity than human PDI. Since domain c of OaPDI is predicted to have a neutral pI, we conclude that this domain does not have to be acidic in nature for PDI to be a functional chaperone. Its redox potential of -157 +/- 4 mV supports a role as a functional oxidoreductase in the plant. The mechanism of enzyme-assisted folding of plant cyclotides was investigated by comparing the folding of kalata B1 derivatives in the presence and absence of OaPDI. OaPDI dramatically enhanced the correct oxidative folding of kalata B1 at physiological pH. A detailed investigation of folding intermediates suggested that disulfide isomerization is an important role of the new plant PDI and is an essential step in the production of insecticidal cyclotides.