Different strategies to enhance the solubility of acylsucrose transferase PaxASAT1 expression in Escherichia coli

Heterologous expression of soluble proteins is a crucial method for studying gene function and enzyme structure. Escherichia coli is a widely used host for expressing foreign genes from plants, animals, and microorganisms. PaxASAT1, a member of the BAHD acyltransferase family, plays a pivotal role in the initial step of acylsucrose biosynthesis by catalyzing the formation of mono-acylsucrose from sucrose and fatty acyl-CoA. In this study, PaxASAT1 was expressed in BL21 (DE3) but with low solubility. Several strategies were evaluated to enhance soluble expression of PaxASAT1, including codon optimization, chaperone co-expression, soluble-tag fusion, and SEP-tag utilization. Results demonstrated that the inclusion of molecular chaperones like DnaK resulted in a slight improvement in the solubility of PaxASAT1. SUMO and MBP tag fusions significantly enhanced PaxASAT1 soluble expression. Notably, C9K-modified SEP tags substantially increased the solubility of PaxASAT1. This study provides a theoretical foundation for the soluble expression of acylsucrose acyltransferase in E. coli , paving the way for further research and applications in the field. • Acylsucrose acyltransferase PaxASAT1 expressed in E. coli with low solubility. • Several strategies has been conducted to improve the solubility of PaxASAT1. • Chaperone protein DnaK improved the solubility to 1.90 fold. • Soluble tags MBP and SUMO improved the protein solubility. • SEP tag C9K combined with SUMO tag improved the solubility of PaxASAT1 to 2.40 fold.