A phage-derived promoter SD13 enables strong and cross-host gene expression in Streptomyces and Escherichia coli

Efficient and tunable promoters are essential tools for metabolic engineering and synthetic biology in Streptomyces . In this study, the lytic bacteriophage phiSASD1 was exploited as a source of novel regulatory elements. Fifteen candidate promoter fragments were identified through bioinformatic prediction and systematically evaluated using a catechol 2,3-dioxygenase ( xylE ) reporter system in Streptomyces lividans TK54 and Escherichia coli JM109. Among these candidates, seven fragments exhibited measurable promoter activity, with P SD13 showing the highest transcriptional strength. In S. lividans , P SD13 displayed up to a 9.79 - fold higher activity than the widely used strong promoter P ermE *, while retaining detectable activity in E. coli , indicating excellent cross-host compatibility. Sequence analysis combined with 5′ RACE revealed that P SD13 possesses a typical σ⁷⁰ - dependent promoter architecture, with its core functional region located between − 70 to + 9 bp relative to the transcription start site. Furthermore, P SD13 efficiently drove the soluble expression of phage endolysin in E. coli , potentially reducing inclusion body formation compared with conventional T7-based expression systems. Collectively, these results identify P SD13 as a phage-derived promoter exhibiting strong activity in both Streptomyces and E. coli , suggesting its potential as a useful genetic element for Streptomyces engineering and heterologous gene expression. Key points • Strong transcriptional promoters were systematically identified from Streptomyces phages. • The novel SD13 promoter shows higher activity than PermE* and works across hosts. • SD13 promoter efficiently expresses soluble heterologous proteins, advancing Streptomyces synthetic biology.