摘要
目的:E蛋白(Protein E,PE)是不可分型流感嗜血杆菌(Nontypeable Haemophilus influenza,NTHi)表面的一种纤溶酶原(plasminogen,Plg)受体,其C末端含有两个赖氨酸残基。NTHi可通过其表面的PE与Plg结合,从而利用机体的纤溶系统深层入侵宿主。基于脂蛋白(a)[Lipoprotein(a),Lp(a)]中载脂蛋白(a)[Apolipoprotein(a),Apo(a)]与Plg高度的同源性,拟证明Lp(a)是否会与重组表达的PE(r PE)结合。方法:原核表达并纯化r PE及敲除C末端两个赖氨酸残基的r PEΔKK,密度梯度离心结合阴离子交换层析分离人血浆Lp(a),通过ELISA、Pull down、Western blot等方法研究r PE与Lp(a)的相互作用。结果:r PE与Lp(a)结合,但不与LDL结合,且r PEΔKK与Lp(a)的结合能力明显低于r PE;赖氨酸类似物6-氨基乙酸(EACA)能有效抑制r PE与Lp(a)的结合;Lp(a)对r PE与Plg的结合具有微弱的抑制作用。结论:r PE能够与Lp(a)结合,其中r PE的C末端赖氨酸残基和Apo(a)的赖氨酸结合位点(lysine binding sites,LBS)是r PE与Lp(a)结合的主要位点。
Objective： Protein E （PE）, with two lysine residues at its C-terminus, is a plasminogen （Plg） receptor on the surface of nontypeable Haemophilus influenza （NTHi）. NTHi can recruit Pig on the cell surface by PE and utilize host fibrinolytic system to achieve its immune invasion. Based on the high homology of Plg and Apolipoprotein （a） [ Apo （a） ] of Lipoprotein （a） [ Lp （a） ], Lp （a） was supposed to bind to PE. Methods： The recombinant PE （rPE） and C-terminal lysine residues-deleted variant （rPE△KK） were obtained by prokaryotic expression and further purified. Lp （a） was isolated and purified from human plasma by KBr density gradient centrifugation followed by Q SepharoseTM Fast Flow ion exchange chromatography. The interaction between rPE and Lp（a） was investigated by enzyme-linked immunosorbent assay（ELISA） and Pull down followed by Western blot. Results： The resuhs indicated that rPE could bind to Lp （a） but not to LDL, and the interaction was significantly inhibited by EACA. The binding capacity of rPEAKK to Lp （a） was obviously lower than that of rPE. In addition, Lp（a） could inhibit the binding of rPE to Pig slightly. Conclusion： In overall, Lp（a） could bind to rPE and the C-terminal lysine residues of rPE and the lysine binding site （ LBS ） of Apo （ a ） was responsible for this interaction.
出处
《中国生物工程杂志》
CAS
CSCD
北大核心
2017年第12期14-20,共7页
China Biotechnology
