Role of dimerization and substrate exclusion in the regulation of bone morphogenetic protein-1 and mammalian tolloid
Role of dimerization and substrate exclusion in the regulation of bone morphogenetic protein-1 and mammalian tolloid
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DOI：
10.1073/pnas.0812178106
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发表时间：
2009-05-26
影响因子：
11.1
通讯作者：
Baldock, Clair
中科院分区：
文献类型：
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作者：
Berry, Richard;Jowitt, Thomas A.;Baldock, Clair
骨形态发生蛋白（BMP）-1/tolloid金属蛋白酶是进化上保守的酶，是背腹模式和组织形态发生的基础。缺乏关于这些蛋白酶如何识别和切割其底物的知识是理解组织组装和胚胎模式的主要障碍。尽管BMP-1和哺乳动物tolloid（mMPs）都是剪接变体，但令人困惑的是，为什么缺少所有其他家族成员中7个非催化结构域中的3个的BMP-1是最有效的蛋白酶。使用单粒子电子显微镜，小角X射线散射，和其他生物物理测量的组合在溶液中，我们表明，mesophageal，但不是BMP-1，形成一个钙离子依赖性二聚体在生理条件下。使用结构域缺失的方法，我们提供的证据表明，EGF 2，这是缺乏BMP-1，是至关重要的二聚体的形成。基于结构和功能数据的组合，我们提出，mesophageal活性是受底物排斥机制。这些结果提供了一个机械的洞察Bmp 1基因的选择性剪接如何产生2种具有不同生物活性的蛋白酶，并在BMP信号传导和组织组装过程中对BMP-1/mRNA和相关蛋白酶的调节具有广泛的意义。
The bone morphogenetic protein (BMP)-1/tolloid metalloproteinases are evolutionarily conserved enzymes that are fundamental to dorsal-ventral patterning and tissue morphogenesis. The lack of knowledge regarding how these proteinases recognize and cleave their substrates represents a major hurdle to understanding tissue assembly and embryonic patterning. Although BMP-1 and mammalian tolloid (mTLD) are splice variants, it is puzzling why BMP-1, which lacks 3 of the 7 noncatalytic domains present in all other family members, is the most effective proteinase. Using a combination of single-particle electron microscopy, small-angle X-ray scattering, and other biophysical measurements in solution, we show that mTLD, but not BMP-1, forms a calcium-ion-dependent dimer under physiological conditions. Using a domain deletion approach, we provide evidence that EGF2, which is absent in BMP-1, is critical to the formation of the dimer. Based on a combination of structural and functional data, we propose that mTLD activity is regulated by a substrate exclusion mechanism. These results provide a mechanistic insight into how alternative splicing of the Bmp1 gene produces 2 proteinases with differing biological activities and have broad implications for regulation of BMP-1/mTLD and related proteinases during BMP signaling and tissue assembly.