Bacterial arylsulfate sulfotransferase as a reporter system

To investigate whether the arylsulfate sulfotransferase (ASST) is suitable as a reporter system for monitoring gene expression, a reporter vector carr ying the fragments of the astA coding region without the promoter region wa s constructed and designated as pSY815. As a test of the ASST reporter syst em's suitability, the regulatory regions of ermC and lacZ were inserted ups tream of the coding region of the reporter gene to generate pSY815-EC and p SY815-LZ, respectively. In the absence of the inserted regulatory regions, the plasmids displayed very low background activities in Bacillus subtilis and Escherichia coli. The ASST activity under the control of the ermC regul atory region was increased 4.4-fold in B. subtilis when induced by 0.1 mu g ml(-1) of erythromycin. These results were consistent with a lacZ reporter gene assay of the ermC regulatory region. Furthermore, we confirmed that th e lacZ promoter in E. coli was strongly induced to a 17.9-fold increase by 0.05 mM of isopropyl-beta -D-thiogalactopyranoside (IPTG) in this reporter system. These results indicate that the ASST is a suitable reporter system. The lack of endogenous activity, the simple detection of enzyme activity i n the living cell, the commercially available non-toxic substrates, and the high sensitivity maize ASST a useful genetic reporter system for monitorin g gene expression and understanding gene regulation.