Structure of homo- and hetero-oligomeric meprin metalloproteases - Dimers, tetramers, and high molecular mass multimers
Structure of homo- and hetero-oligomeric meprin metalloproteases - Dimers, tetramers, and high molecular mass multimers
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DOI：
10.1074/jbc.m208808200
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发表时间：
2003-01-24
影响因子：
4.8
通讯作者：
Bond, JS
中科院分区：
文献类型：
--
作者：
Bertenshaw, GP;Norcum, MT;Bond, JS
Meprin A 和 B 是由进化相关的 α 和/或 β 亚基组成的金属蛋白酶，是由肾和肠上皮细胞、白细胞和癌细胞表达的膜结合和分泌酶。先前的工作证实，多结构域 meprin 亚基（每个类似于 80 kDa）形成二硫桥同源二聚体和异源二聚体，并且底物和肽键特异性不同。本文的工作清楚地表明meprin二聚体的寡聚能力显着不同。使用电泳、光散射、尺寸排阻色谱和电子显微镜来表征重组大鼠 meprins 的四级结构。 Meprin B 仅由 meprin β 亚基组成，在多种条件下呈二聚体。相比之下，meprin α 同二聚体形成包含多达 100 个亚基的异质多聚体（环、环状、螺旋和管状结构），蛋白质峰处的分子量范围约为 1.0 至 6.0 MDa。 meprin α 同源寡聚物的大小取决于蛋白质浓度、离子强度和活化状态。 Meprin Alphata 异二聚体倾向于形成四聚体，但不形成更高的寡聚体。因此，体内具有跨膜结构域的meprin β的存在限制了meprin分子的寡聚化潜力并将meprin定位于质膜。相比之下，分泌的meprin α同型二聚体倾向于自缔合，将蛋白水解潜力集中到高分子量多聚体中，从而允许自动区室化。这项工作表明存在不同的机制来定位和集中膜结合和分泌的 meprin 金属蛋白酶的蛋白水解活性。
Meprin A and B, metalloproteases consisting of evolutionarily related alpha and/or beta subunits, are membrane-bound and secreted enzymes expressed by kidney and intestinal epithelial cells, leukocytes, and cancer cells. Previous work established that the multidomain meprin subunits (each similar to80 kDa) form disulfide-bridged homo-and heterodimers, and differ in substrate and peptide bond specificities. The work herein clearly demonstrates that meprin dimers differ markedly in their ability to oligomerize. Electrophoresis, light scattering, size exclusion chromatography, and electron microscopy were used to characterize quaternary structures of recombinant rat meprins. Meprin B, consisting of meprin beta subunits only, was dimeric under a wide range of conditions. By contrast, meprin alpha homodimers formed heterogeneous multimers (ring-, circle-, spiral-, and tube-like structures) containing up to 100 subunits, with molecular masses at protein peaks ranging from similar to1.0 to 6.0 MDa. The size of the meprin alpha homo-oligomers was dependent on protein concentration, ionic strength, and activation state. Meprin alphabeta heterodimers tended to form tetramers but not higher oligomers. Thus, the presence of meprin beta, which has a transmembrane domain in vivo, restricts the oligomerization potential of meprin molecules and localizes meprins to the plasma membrane. By contrast, the propensity of secreted meprin alpha homodimers to self-associate concentrates proteolytic potential into high molecular mass multimers and thus allows for autocompartmentalization. The work indicates that different mechanisms exist to localize and concentrate the proteolytic activity of membrane-bound and secreted meprin metalloproteinases.