A minimized human integrin α5β1 that retains ligand recognition
A minimized human integrin α5β1 that retains ligand recognition
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DOI：
10.1074/jbc.275.8.5888
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发表时间：
2000-02-25
影响因子：
4.8
通讯作者：
Parello, J
中科院分区：
文献类型：
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作者：
Banères, JL;Roquet, F;Parello, J
基于CD证据，从人整联蛋白α（5）β（1）分离的两个重组片段分别包含α（5）的FG-GAP重复序列III至VII和β（1）的插入型结构域，在溶液中结构明确。二价阳离子结合诱导构象适应，其通过Ca 2+或Mg 2+（或Mn 2+）与α（5）实现，并且仅通过Mg 2+（或Mn 2+）与β（1）实现。基于水NMR弛豫，与β（1）结合的Mn 2+是高度水合的（类似于3个水分子），与金属离子依赖性粘附位点型金属配位一致。用Mg 2+（或Mn 2+）饱和的每个片段以RGD依赖性方式结合重组纤连蛋白配体。基于CD，当与α（5）片段结合而不是与β（1）片段结合时，纤连蛋白配体上诱导构象重排。配体结合导致金属离子从β（1）置换。α（5）和β（1）片段形成稳定的异源二聚体（α（5）β（1）微整联蛋白），其在Mg 2+存在下保留配体识别以形成1：1：1三元复合物，并诱导纤连蛋白配体的特异性构象适应。使用低分子量RGD模拟物从我们的数据推断出RGD与α和β整联蛋白组分结合的双位点模型。
Two isolated recombinant fragments from human integrin alpha(5)beta(1) encompassing the FG-GAP repeats III to VII of alpha(5) and the insertion-type domain from beta(1), respectively, are structurally well defined in solution, based on CD evidence. Divalent cation binding induces a conformational adaptation that is achieved by Ca2+ or Mg2+ (or Mn2+) with alpha(5) and only by Mg2+ (or Mn2+) with beta(1). Mn2+ bound to beta(1) is highly hydrated (similar to 3 water molecules), based on water NMR relaxation, in agreement with a metal ion-dependent adhesion site-type metal coordination. Each fragment saturated with Mg2+ (or Mn2+) binds a recombinant fibronectin ligand in an RGD-dependent manner. A conformational rearrangement is induced on the fibronectin ligand upon binding to the alpha(5), but not to the beta(1) fragment, based on CD, Ligand binding results in metal ion displacement from beta(1). Both alpha(5) and beta(1) fragments form a stable heterodimer (alpha(5)beta(1) mini-integrin) that retains ligand recognition to form a 1:1:1 ternary complex, in the presence of Mg2+, and induces a specific conformational adaptation of the fibronectin ligand, A two-site model for RGD binding to both alpha and beta integrin components is inferred from our data using low molecular weight RGD mimetics.