Industrial Biotechnology & Bioenergy Research Center, KRIBB, Daejeon 305-806, Republic of Korea.
J Biotechnol. 2010 Aug 20;149(1-2):16-20. doi: 10.1016/j.jbiotec.2010.06.021. Epub 2010 Jun 30.
Bacillus thuringiensis produces crystal proteins (Cry) that account for up to 25% of the dry cell weight during the stationary phase. The high-level expression and stationary phase-specific autoinduction of the cry gene led to development of a cry promoter-based Bacillus expression system. Among the various cry promoters, cry3Aa promoter was selected by comparing the lacZ expression levels in Bacillus subtilis. An extracellular enzyme cellulase was highly upregulated during the stationary phase while under control of the cry3Aa promoter. Improvement of the cry3Aa promoter was obtained by modification of the promoter sequence. Specifically, a 5-fold increase in lacZ expression was obtained by changing both the -35 and -10 boxes of the cry3Aa promoter to the consensus sequence of the sigma(A)-dependent promoter of B. subtilis. The modified cry3Aa promoter produced a significantly higher yield of AprE, which suggests that the promoter may be useful for high-level protein expression in B. subtilis.
苏云金芽孢杆菌在静止期产生晶体蛋白（Cry），占细胞干重的 25%。Cry 基因的高水平表达和静止期特异性自动诱导导致了基于 Cry 启动子的芽孢杆菌表达系统的发展。在各种 Cry 启动子中，Cry3Aa 启动子通过比较枯草芽孢杆菌中 lacZ 的表达水平来选择。在静止期，Cry3Aa 启动子控制下的细胞外酶纤维素酶被高度上调。通过修饰启动子序列获得了 Cry3Aa 启动子的改进。具体来说，通过将 Cry3Aa 启动子的-35 和-10 框更改为枯草芽孢杆菌依赖于 sigma(A)的启动子的共有序列，获得了 lacZ 表达的 5 倍增加。修饰后的 Cry3Aa 启动子产生了 AprE 的产量显著增加，这表明该启动子可能对枯草芽孢杆菌中高水平蛋白质表达有用。
