Prior Stephen H, Fulcher Yan G, Koppisetti Rama K, Jurkevich Alexander, Van Doren Steven R
Biochemistry Department, University of Missouri, 117 Schweitzer Hall, Columbia, MO 65211, USA.
Molecular Cytology Core, 120 Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA.
Structure. 2015 Nov 3;23(11):2099-110. doi: 10.1016/j.str.2015.08.013. Epub 2015 Oct 1.
Matrix metalloproteinase-7 (MMP-7) sheds signaling proteins from cell surfaces to activate bacterial killing, wound healing, and tumorigenesis. The mechanism targeting soluble MMP-7 to membranes has been investigated. Nuclear magnetic resonance structures of the zymogen, free and bound to membrane mimics without and with anionic lipid, reveal peripheral binding to bilayers through paramagnetic relaxation enhancements. Addition of cholesterol sulfate partially embeds the protease in the bilayer, restricts its diffusion, and tips the active site away from the bilayer. Its insertion of hydrophobic residues organizes the lipids, pushing the head groups and sterol sulfate outward toward the enzyme's positive charge on the periphery of the enlarged interface. Fluorescence probing demonstrates a similar mode of binding to plasma membranes and internalized vesicles of colon cancer cells. Binding of bilayered micelles induces allosteric activation and conformational change in the auto-inhibitory peptide and the adjacent scissile site, illustrating a potential intermediate in the activation of the zymogen.
基质金属蛋白酶-7（MMP-7）从细胞表面释放信号蛋白，以激活细菌杀伤、伤口愈合和肿瘤发生。针对可溶性MMP-7靶向细胞膜的机制已得到研究。酶原的核磁共振结构，游离状态以及与有无阴离子脂质的膜模拟物结合的状态，通过顺磁弛豫增强揭示了其与双层膜的外周结合。添加硫酸胆固醇会使蛋白酶部分嵌入双层膜中，限制其扩散，并使活性位点远离双层膜。其疏水残基的插入使脂质有序排列，将头部基团和硫酸甾醇向外推向扩大界面外围酶的正电荷。荧光探测表明其与结肠癌细胞的质膜和内化囊泡具有相似的结合模式。双层胶束的结合诱导自抑制肽和相邻的可裂解位点发生变构激活和构象变化，说明了酶原激活过程中的一个潜在中间体。
