Purification, biochemical characterization, and cloning of phospholipase D from Streptomyces racemochromogenes strain 10-3.

We previously isolated Streptomyces racemochromogenes strain 10-3, which produces a phospholipase D (PLD) with high transphosphatidylation activity. Here, we purified and cloned the PLD (PLD103) from the strain. PLD103 exerted the highest hydrolytic activity at a slightly alkaline pH, which is in contrast to the majority of known Streptomyces PLDs that have a slightly acidic optimum pH. PLD103 shares only 71-76% amino acid sequence identity with other Streptomyces PLDs that have a slightly acidic optimum pH; thus, the diversity in the primary structure might explain the discrepancy observed in the optimum pH. The purified PLD displayed high transphosphatidylation activity in the presence of glycerol, L: -serine, and 2-aminoethanol hydrochloride with a conversion rate of 82-97% in a simple one-phase system, which was comparable to the rate of other Streptomyces PLDs in a complicated biphasic system.