Kuroita Toshihiro, Kanno Takuya, Kawai Atsushi, Kawakami Bunsei, Oka Masanori, Endo Yaeta, Tozawa Yuzuru
Graduate School of Science and Engineering, Ehime University, Bunkyo-cho, Matsuyama, Ehime, 790-8577, Japan.
Extremophiles. 2007 Jan;11(1):85-94. doi: 10.1007/s00792-006-0015-4. Epub 2006 Aug 8.
We have isolated and characterized a gene for a putative protein-disulfide oxidoreductase (phdsb) in the archaeon Pyrococcus horikoshii. The open reading frame of phdsb encodes a protein of 170 amino acids with an NH(2)-terminal extension similar to the bacterial signal peptides. The putative mature region of PhDsb includes a sequence motif, Cys-Pro-His-Cys (CPHC), that is conserved in members of the bacterial DsbA family, but otherwise the archaeal and bacterial sequences do not show substantial similarity. A recombinant protein corresponding to the predicted mature form of PhDsb behaved as a monomer and manifested oxidoreductase activities in vitro similar to those of DsbA of Escherichia coli. The catalytic activity of PhDsb was thermostable and was shown by mutation analysis to depend on the NH(2)-terminal cysteine residue of the CPHC motif. Thus, in spite of their low overall sequence similarities, DsbA-like proteins of archaea and bacteria appear to be highly similar in terms of function.
我们已经从嗜热栖热球菌中分离并鉴定了一个假定的蛋白质二硫键氧化还原酶（phdsb）基因。phdsb的开放阅读框编码一个由170个氨基酸组成的蛋白质，其NH(2)末端延伸类似于细菌信号肽。PhDsb的假定成熟区域包含一个序列基序Cys-Pro-His-Cys（CPHC），该基序在细菌DsbA家族成员中保守，但古细菌和细菌序列在其他方面没有显示出实质性的相似性。与预测的PhDsb成熟形式相对应的重组蛋白表现为单体，并在体外表现出与大肠杆菌DsbA相似的氧化还原酶活性。PhDsb的催化活性具有热稳定性，突变分析表明其活性依赖于CPHC基序的NH(2)末端半胱氨酸残基。因此，尽管古细菌和细菌的DsbA样蛋白总体序列相似性较低，但在功能方面似乎高度相似。
