Nakamura K, Itoh Y, Yamane K
Institute of Biological Sciences, University of Tsukuba, Ibaraki.
J Biochem. 1988 Aug;104(2):265-9. doi: 10.1093/oxfordjournals.jbchem.a122455.
Prediction of the secondary structure, a sequence of 33 amino acids, for the Bacillus subtilis alpha-amylase signal peptide suggested the presence of a beta-turn structure in it. Through substitution of Gly27 and/or Pro28 with Ala residues by means of the site-directed mutagenesis method, the secondary structure was predicted to consist of an alpha-helix conformation throughout the signal peptide containing a small region of random coil. The effect of the structural modification upon the secretion of proteins was analyzed as to the production of beta-lactamase after the DNA regions encoding the parental and modified signal peptides had been fused in frame to the DNA fragment for the beta-lactamase using HindIII linker DNA. The production of beta-lactamase increased to 4 to 6 times in B. subtilis cells and to 1.5 to 2.0 times in Escherichia coli with the modified signal peptides. The modification of the signal peptide affected the transcription level of the fused genes.
对枯草芽孢杆菌α-淀粉酶信号肽（一段由33个氨基酸组成的序列）的二级结构预测表明，其中存在一个β-转角结构。通过定点诱变方法将甘氨酸27和/或脯氨酸28用丙氨酸残基取代后，预测二级结构在整个信号肽中由α-螺旋构象组成，其中包含一小段随机卷曲区域。在使用HindIII连接子DNA将编码亲本和修饰信号肽的DNA区域与β-内酰胺酶的DNA片段进行读框融合后，分析了结构修饰对蛋白质分泌的影响，具体是关于β-内酰胺酶的产生情况。使用修饰后的信号肽时，枯草芽孢杆菌细胞中β-内酰胺酶的产量增加到4至6倍，大肠杆菌中增加到1.5至2.0倍。信号肽的修饰影响了融合基因的转录水平。
