Tangrea Michael A, Bryan Philip N, Sari Nese, Orban John
Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, 9600 Gudelsky Drive, Rockville, MD 20850, USA.
J Mol Biol. 2002 Jul 19;320(4):801-12. doi: 10.1016/s0022-2836(02)00543-0.
The solution structure of the mouse pro-hormone convertase (PC) 1 pro-domain was determined using heteronuclear NMR spectroscopy and is the first structure to be obtained for any of the domains in the convertase family. The ensemble of NMR-derived structures shows a well-ordered core consisting of a four-stranded antiparallel beta-sheet with two alpha-helices packed against one side of this sheet. Sequence homology suggests that the other eukaryotic PC pro-domains will have the same overall fold and most of the residues forming the hydrophobic core of PC1 are highly conserved within the PC family. However, some of the core residues are predicted by homology to be replaced by polar amino acid residues in other PC pro-domains and this may help to explain their marginal stability. Interestingly, the folding topology observed here is also seen for the pro-domain of bacterial subtilisin despite little or no sequence homology. Both the prokaryotic and eukaryotic structures have hydrophobic residues clustered on the solvent-accessible surface of their beta-sheets although the individual residue types differ. In the bacterial case this region is buried at the binding interface with the catalytic domain and, in the eukaryotic PC family, these surface residues are conserved. We therefore propose that the hydrophobic patch in the PC1 pro-domain is involved in the binding interface with its cognate catalytic domain in a similar manner to that seen for the bacterial system. The PC1 pro-domain structure also reveals potential mechanisms for the acid-induced dissociation of the complex between pro- and catalytic domains.
利用异核核磁共振光谱法确定了小鼠前激素转化酶（PC）1前结构域的溶液结构，这是转化酶家族中任何一个结构域获得的首个结构。核磁共振衍生结构的集合显示出一个有序的核心，由一个四链反平行β折叠片层组成，有两个α螺旋堆积在该片层的一侧。序列同源性表明，其他真核PC前结构域将具有相同的整体折叠，并且形成PC1疏水核心的大多数残基在PC家族中高度保守。然而，通过同源性预测，其他PC前结构域中的一些核心残基将被极性氨基酸残基取代，这可能有助于解释它们的边缘稳定性。有趣的是，尽管序列同源性很少或没有，但在这里观察到的折叠拓扑结构在细菌枯草杆菌蛋白酶的前结构域中也能看到。原核和真核结构在其β折叠片层的溶剂可及表面都有疏水残基聚集，尽管个别残基类型不同。在细菌的情况下，该区域埋在与催化结构域的结合界面处，而在真核PC家族中，这些表面残基是保守的。因此，我们提出PC1前结构域中的疏水补丁以与细菌系统类似的方式参与与其同源催化结构域的结合界面。PC1前结构域结构还揭示了酸诱导前结构域和催化结构域之间复合物解离的潜在机制。
