Characterisitics and gene cloning of phospholipase D of the psychrophile, Shewanella sp.

Phospholipase D, with a molecular mass of 64 kDa, was purified from the psychrophile, Shewanella sp. The enzyme showed maximal activity at pH 7.8 and 40 degrees C in the presence of the Ca2+-ion, and its activity at 10 degrees C was 6.5% of maximum. The enzyme exhibited high activity to the non-micelle form of phosphatidylcholine in an aqueous solution containing water miscible alcohols such as methanol, ethanol, iso-propanol, and n-propanol. Nucleotide sequencing of the enzyme gene yielded a deduced amino acid sequence, which showed 36.2% identity to that of Streptomyces chromofuscus phospholipase D alone. The low sequence similarity to other phospholipase D enzymes suggests that the purified enzyme might be a novel phospholipase D.