猪链球菌2型丝氨酸/苏氨酸磷酸酶的鉴定和特性分析

Identification and characterization of serine /threonine phosphatase of Streptococcus suis type 2

利用PCR扩增猪链球菌2型强毒株SS2-1丝氨酸/苏氨酸磷酸酶(STP)的编码基因,克隆到表达载体pET-30a(+),在大肠杆菌BL21中进行原核表达,获得重组蛋白质rSsSTP。重组蛋白质经His蛋白质层析柱纯化后,利用pNPP分析rSsSTP的酶活性。结果显示rSsSTP为Mn2+依赖的磷酸酶,最适离子浓度为2 mmol/L,最佳反应温度为37℃,最佳pH值为8.0。

In this study, the complete serine/threonine phosphatase （ STP） gene was amplified by PCR from the ge-nome of virulent strain SS2-1 of Streptococcus suis type 2, and cloned into expresssion vector pET-30a（＋）. The recombi-nant SsSTP protein （ rSsSTP） was induced by IPTG to express in E. coli BL21 and purified using HisTrap columns. The ac-tivity of rSsSTP was tested using p-nitrophenyl phosphate （ pNPP） as a substrate. rSsSTP was a manganese-dependent phos-phatase in the presence of Mn2＋at 2 mmol/L concentration; the optimal temperature was 37 ℃,and the optimal pH value was 8. 0.