Effective Expression of the Serratia marcescens Phospholipase A1 Gene in Escherichia coli BL21(DE3), Enzyme Characterization, and Crude Rapeseed Oil Degumming via a Free Enzyme Approach

N-terminal truncated phospholipase A1 accessory protein PlaS from Serratia marcescens alleviates inhibitory on host cell growth and enhances PlaA1 enzymatic activity

Phospholipase A1 (PLA1) is a kind of specific phospholipid hydrolase widely used in food, medical, textile. However, limitations in its expression and enzymatic activity have prompted the investigation of the phospholipase-assisting protein PlaS. In this study, we elucidate the role of PlaS in enhancing the expression and activity of PlaA1 through N-terminal truncation. Our research demonstrates that truncating the N-terminal region of PlaS effectively overcomes its inhibitory effect on host cells, resulting in improved cell growth and increased protein solubility of the protein. The yeast two-hybrid assay confirms the interaction between PlaA1 and N-terminal truncated PlaS (∆N27 PlaS), highlighting their binding capabilities. Furthermore, in vitro studies using Biacore analysis reveal a concentration-dependent and specific binding between PlaA1 and ∆N27 PlaS, exhibiting high affinity. Molecular docking analysis provides insights into the hydrogen bond interactions between ∆N27 PlaS and PlaA1, identifying key amino acid residues crucial for their binding. Finally, the enzyme activity of PLA1 was boost to 8.4 U/mL by orthogonal test. Study significantly contributes to the understanding of the interaction mechanism between PlaS and PlaA1, offering potential strategies for enhancing PlaA1 activity through protein engineering approaches.

Efficient production of a novel alkaline cold-active phospholipase C from Aspergillus oryzae by molecular chaperon co-expression for crude oil degumming

A novel alkaline cold-active phospholipase C (PLC) gene (AoPC) from Aspergillus oryzae was cloned. AoPC exhibited the highest sequence similarity of 32.5% with that of a PLC from Arabidopsis thaliana. The gene was co-expressed in Pichia pastoris with molecular chaperone PDI (protein disulfide isomerases), and the highest PLC activity of 82, 782 U mL^-1 was achieved in a 5-L fermentor. The recombinant enzyme (AoPC) was most active at pH 8.0 and 25 °C, respectively, and it was stable over a broad pH range of 4.5-9.0 and up to 40 °C. It is the first fungal alkaline PLC. The application of AoPC (with 25% citric acid, w/w) in oil degumming process significantly reduced the phosphorus of crude soybean oil by 93.3% to a commercially acceptable level (<10 mg kg^-1). Therefore, the relatively high yield and excellent properties of AoPC may possess it great potential in crude oil refining industry.

Expression, purification and biophysical characterization of recombinant Streptomyces violaceoruber phospholipase PLA2 overproduced in Pichia pastoris

Aim: The main purpose of this work was to develop new protocols for high yield purification of secretory phospholipase A2 (PLA2) and to investigate its biophysical properties.Materials and methods: We have used a Pichia pastoris expression system for PLA2 expression and two-stage chromatography for its purification. The biophysical properties of PLA2 were investigated by circular dichroism.Results: A scalable method for high yield purification of recombinant Streptomyces violaceruber PLA2 was developed. The PLA2 from S. violaceruber was expressed in the methylotrophic yeast P. pastoris. Functional active phospholipase A2 with specific activity 73 U/mg was purified with a concentration of at least 3 mg/mL. The role of different divalent ions in PLA2 thermostability were evaluated. Ca²⁺ and Ba²⁺ ions significantly increased thermostability of the enzyme.