Hatanaka Tadashi, Negishi Tomofumi, Kubota-Akizawa Megumi, Hagishita Tairo
Research Institute for Biological Sciences, Okayama (RIBS), 7549-1 Kayo-cho, Jyobo-gun, Okayama, Japan.
Biochim Biophys Acta. 2002 Jul 29;1598(1-2):156-64. doi: 10.1016/s0167-4838(02)00363-1.
Four phospholipases D (PLDs) in the culture supernatants from Streptomyces strains were purified to conduct a comparative study of their thermostabilities. Among the four purified PLDs, the enzyme from Streptomyces halstedii K1 lost its activity at 45 degrees C. PLD from Streptomyces septatus TH-2 was stable at the same temperature. We determined the nucleotide sequence encoding the PLD gene from S. halstedii K1 (K1PLD). The deduced amino acid sequence showed high homology to that of the PLD gene from S. septatus TH-2 (TH-2PLD). By comparison of the optimum temperature and the thermostability among recombinant PLDs, K1PLD, TH-2PLD and T/KPLD that possessed the N-terminus of TH-2PLD and the C-terminus of K1PLD, T/KPLD showed the properties midway between those of K1PLD and TH-2PLD. It was suggested that the 176 amino acids at C-terminus of Streptomyces PLD were important for its thermostability.
对链霉菌菌株培养上清液中的四种磷脂酶D（PLD）进行了纯化，以对它们的热稳定性进行比较研究。在这四种纯化的PLD中，来自哈氏链霉菌K1的酶在45℃时失去活性。来自隔链霉菌TH-2的PLD在相同温度下稳定。我们确定了哈氏链霉菌K1（K1PLD）中编码PLD基因的核苷酸序列。推导的氨基酸序列与隔链霉菌TH-2（TH-2PLD）的PLD基因的氨基酸序列具有高度同源性。通过比较重组PLD、K1PLD、TH-2PLD以及具有TH-2PLD N端和K1PLD C端的T/KPLD之间的最适温度和热稳定性，T/KPLD表现出介于K1PLD和TH-2PLD之间的特性。提示链霉菌PLD C端的176个氨基酸对其热稳定性很重要。
