Cloning and expression of phospholipase D genepld fromStreptomyces chromofuscus

The phospholipase D (PLD) gene pld encoding the mature PLD enzyme from Streptomyces chromofuscus was cloned and sequenced. The recombinant protein has been expressed in Escherichia coli and purified. The yield of aim protein was up to 27.5 mg/l culture medium. Because it was targeted with a 6 × his-tag, the recombinant protein could be much more easily purified by using Ni-NTA His·Bind Purification Kits. After concentration, the concentration of rPLD was 1.0 mg/ml buffer. With transphosphatidylation activity of rPLD, phosphatidylserine (PS) could be produced from phosphatidylcholine (PC). The optimum organic phase was chloroform, optimum pH was 7.5, optimum temperature and time of transphosphatidylation reaction that catalysed by rPSS were 30 °C and 6 h, respectively. The highest transphosphatidylation rate of rPSS was up to 31% and the specific enzyme activity was up to 39 U/mg.