Evaluation of staphylococcus aureus class C non-specific acid phosphatase (SapS) as a reporter for gene expression and protein secretion in gram-negative and gram-positive bacteria

Abstract

A phosphatase secreted by Staphylococcus aureus strain 154 has previously been characterized and classified as a new member of the bacterial class C family of non-specific acid phosphatases. As the acid phosphatase activity can be easily detected using a cost-effective plate screen, quantitatively measured by a simple enzyme assay and detected with zymography, its potential use as a reporter system was investigated. The S. aureus acid phosphatase (sapS) gene has been cloned and expressed from its own regulatory sequences in Escherichia coli, Bacillus subtilis and Bacillus halodurans. Transcriptional and translational fusions of the sapS gene with selected heterologous promoters and signal sequences were constructed and expressed in all three the host strains. The strongest promoter for heterologous protein production in each of the host strains was identified, i.e. the E. coli lacZ promoter in E. coli, the B. halodurans alkaline protease promoter in B. subtilis and the B. halodurans sD promoter in B. halodurans. This is the first report on the development of a Class C acid phosphatase gene as a reporter gene with the advantage of being able to function in both Gram-positive and Gram-negative host strains