Genetic characteristics of novel extreme alkaline-inducible promoter located in five prime upstream region of peptidyl-prolyl cis/trans isomerase from Vibrio anguillarum

Abstract Vibrio has attracted attention as a promising genetic chassis in the field of synthetic biology. FK506 binding protein (FKBP)-type peptidyl-prolyl cis/trans isomerase (PPIase) is involved in protein folding. In this study, we report, for the first time, the promoter regions in Vibrio that drive increased FKBP expression in the extremely alkaline environment. Proteomic analysis of V. anguillarum NB10 showed that VaFKBP was significantly upregulated under extreme alkaline stress (pH 10) condition. Additionally, the putative core promoter-containing regions and a reporter gene coding a β-galactosidase were introduced into the Escherichia coli system, which showed β-galactosidase activity of 61.47 ± 2.91 and 95.83 ± 6.76 Miller unit (MU) at pH 9 and 10, respectively, after 4 h of stress. This outcome was 1.97- and 2.88-fold higher that that observed under normal conditions of 25°C and pH 7 (31.27 ± 1.15 MU). To the best of our knowledge, this is the first report of a promoter showing increased expression under extremely alkaline conditions. We believe that this is a useful chassis in promoter engineering and can be used as a powerful tool for activating transcriptionally silent biosynthetic gene clusters in specific environments.