Leu122对Hsp16.3组装过程中亚基相互作用的影响

The Effect of Leu122 on the Subunit Interaction in the Reassembly of Hsp16.3 in vitro

小分子热休克蛋白是种类最多的热休克蛋白家族 ,它们均以寡聚体的形式存在 .研究表明 ,来自结核杆菌的小分子热休克蛋白Hsp16 3是以 3个三聚体的形式存在的九聚体 .为了探讨Hsp16 3体外组装过程中的亚基相互作用和识别 ,利用野生型Hsp16 3及其L12 2A突变体蛋白为模型 ,采用高效液相分子筛层析、非变性聚丙烯酰胺凝胶电泳和脲梯度凝胶电泳等方法进行研究 .结果表明 ,Hsp16 3在体外能自发地再组装成九聚体 .12 2位的亮氨酸残基对Hsp16 3体外再组装过程中的亚基相互作用有重要的影响 ,并且在Hsp16 3的组装过程中 ,亚基之间的相互识别是高度灵敏和特异的 ,野生型蛋白的亚基和L12 2A突变体蛋白的亚基并不能形成杂合体 。

Small heat shock proteins,a family of heat shock proteins ubiquitously present both in prokaryotes and eukaryotes,form specific oligomeric structures of 200—800 kD,with the monomer size between 12 and 43 kD.The small heat shock protein from \%Mycobacterium tuberculosis\%,Hsp16\^3 was previously shown to form a specific nonameric structure,existing as a trimer of trimers.The subunit interaction in the reassembly process of this oligomeric protein was investigated using wild type Hsp16\^3 and the L122A mutant protein,non\|denaturing polyacrylamide gel electrophoresis and urea gradient polyacrylamide gel electrophoresis.The results show that Leu122 plays an important role in the subunit interaction in the assembly process of Hsp16\^3.There are no hybrid intermediates formed during the \%in vitro\% co\|assembly process of wild type Hsp16\^3 and the L122A mutant,which strongly suggests that only identical subunites of Hsp16\^3 can specifically recognize each other and form oligomer.