MacIntyre S, Eschbach M L, Mutschler B
Max-Planck-Institut für Biologie, Tübingen, Federal Republic of Germany.
Mol Gen Genet. 1990 May;221(3):466-74. doi: 10.1007/BF00259413.
Export of the outer membrane protein, OmpA, across the cytoplasmic membrane of Escherichia coli was severely inhibited by the presence of two, three, four or six additional basic residues at the N-terminus of the mature polypeptide, but not by three similarly positioned acidic residues. Because a few bacterial proteins do possess basic residues close to the leader peptidase cleavage site and because the type of inhibition described here could pose problems in the construction of hybrid secretory proteins, we also studied means of alleviating this form of export incompatibility. Inhibition was abolished when basic residues were preceded by acidic ones. Also, the processing rates of the mutants with two or six basic residues could be partially restored by increasing the length of the hydrophobic core of the signal peptide. Taking this as a precedent, it is suggested that the structure of the signal peptide is an important feature for maintenance of a reasonable rate of translocation of those exported proteins which possess basic residue(s) at the N-terminus of the mature polypeptide.
在成熟多肽的N端存在两个、三个、四个或六个额外的碱性残基时，大肠杆菌外膜蛋白OmpA穿过细胞质膜的输出受到严重抑制，但三个位置类似的酸性残基不会导致这种抑制。由于一些细菌蛋白在靠近前导肽酶切割位点处确实含有碱性残基，并且由于此处描述的抑制类型可能会在构建杂合分泌蛋白时带来问题，因此我们还研究了减轻这种输出不相容形式的方法。当碱性残基之前存在酸性残基时，抑制作用消失。此外，通过增加信号肽疏水核心的长度，可以部分恢复具有两个或六个碱性残基的突变体的加工速率。以此为先例，有人提出信号肽的结构是维持那些在成熟多肽N端具有碱性残基的输出蛋白合理转运速率的一个重要特征。
