Lee Y C, Koike H, Taguchi H, Ohta T, Matsuzawa H
Department of Agricultural Chemistry, University of Tokyo, Japan.
FEMS Microbiol Lett. 1994 Jul 1;120(1-2):69-74. doi: 10.1111/j.1574-6968.1994.tb07009.x.
Thermus thermophilus cells harboring an expression plasmid for the aqualysin I gene secrete the mature enzyme into the medium. In an Escherichia coli expression system, a precursor of the enzyme with the C-terminal pro-sequence is accumulated in the cells, and upon treatment at 65 degrees C the active enzyme is produced. One- to 10-amino acid residue deletions, as well as complete 105-residue deletion of the C-terminal pro-sequence from the C-terminus, did not affect the production of the enzyme in E. coli cells. T. thermophilus cells harboring plasmids for mutant precursors with one- and three-residue deletions secreted the enzyme extracellularly. However, transformants harboring plasmids for mutant precursors with deletions of five or more amino acid residues could not be obtained. These results suggest that the C-terminal pro-sequence plays an important role in the extracellular secretion of the enzyme in T. thermophilus cells.
携带嗜热栖热菌溶素I基因表达质粒的嗜热栖热菌细胞将成熟酶分泌到培养基中。在大肠杆菌表达系统中，带有C端前导序列的酶前体在细胞中积累，并且在65℃处理后产生活性酶。从C端进行1至10个氨基酸残基的缺失，以及C端前导序列完全缺失105个残基，均不影响该酶在大肠杆菌细胞中的产生。携带具有1个和3个残基缺失的突变前体质粒的嗜热栖热菌细胞将该酶分泌到细胞外。然而，无法获得携带具有5个或更多氨基酸残基缺失的突变前体质粒的转化体。这些结果表明，C端前导序列在嗜热栖热菌细胞中该酶的细胞外分泌中起重要作用。
