Ligation of the Fibrin-binding Domain by β-Strand Addition Is Sufficient for Expansion of Soluble Fibronectin
Ligation of the Fibrin-binding Domain by β-Strand Addition Is Sufficient for Expansion of Soluble Fibronectin
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DOI：
10.1074/jbc.m111.294041
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发表时间：
2012-04-13
影响因子：
4.8
通讯作者：
Mosher, Deane F.
中科院分区：
文献类型：
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作者：
Maurer, Lisa M.;Ma, Wenjiang;Mosher, Deane F.
纤连蛋白 (FN) 如何从致密血浆蛋白转化为细胞外基质的纤维成分尚不清楚。 “功能上游结构域”(FUD)是一种基于化脓性链球菌F1粘附素的多肽，通过反平行β链添加到不连续组的N端FN I型模块、纤维蛋白结合结构域的2-5FNI和明胶结合结构域的8-9FNI来结合。这种结合阻碍了 FN 的组装。为了了解 2-5FNI、8-9FNI 或两组组合的连接对于抑制是否重要，我们测试了“高亲和力下游结构域”(HADD)，它通过添加 β 链与连续的 FNI 模块集 1-5FNI（包含纤维蛋白结合结构域）结合。 HADD 和 FUD 在阻断纤连蛋白组装方面具有类似的活性。 HADD 或 FUD 与可溶性血浆 FN 的结合将第十个 FN III 型模块 ((FNIII)-F-10) 中的表位暴露于单克隆抗体 mAbIII-10，并引起 FN 的扩张（通过动态光散射评估）。在 (FNI)-F-9 或 (FNIII)-F-3 之后截短的可溶性 N 端构建体比可溶性 FN 更好地竞争 FUD 或 HADD 与吸附的 FN 的结合，表明涉及 III 型模块的相互作用比 (FNIII)-F-3 更能限制 β 链添加到完整可溶性 FN 内的 1-5FNI。 FN 与 mAbIII-10 或肝素预孵育可适度增加与 HADD 或 FUD 的结合。因此，参与整合素和糖胺聚糖（FNIII）-F-10和12-14FNIII结合的FNIII模块的连接增加了1-5FNI的可及性。 1-5FNI、(FNIII)-F-10 和 12-14FNIII 之间的约束相互作用的变构损失可能使得 FN 组装成细胞外原纤维。
How fibronectin (FN) converts from a compact plasma protein to a fibrillar component of extracellular matrix is not understood. "Functional upstream domain" (FUD), a polypeptide based on F1 adhesin of Streptococcus pyogenes, binds by anti-parallel beta-strand addition to discontinuous sets of N-terminal FN type I modules, 2-5FNI of the fibrin-binding domain and 8-9FNI of the gelatin-binding domain. Such binding blocks assembly of FN. To learn whether ligation of 2-5FNI, 8-9FNI, or the two sets in combination is important for inhibition, we tested "high affinity downstream domain" (HADD), which binds by beta-strand addition to the continuous set of FNI modules, 1-5FNI, comprising the fibrin-binding domain. HADD and FUD were similarly active in blocking fibronectin assembly. Binding of HADD or FUD to soluble plasma FN exposed the epitope to monoclonal antibody mAbIII-10 in the tenth FN type III module ((FNIII)-F-10) and caused expansion of FN as assessed by dynamic light scattering. Soluble N-terminal constructs truncated after (FNI)-F-9 or (FNIII)-F-3 competed better than soluble FN for binding of FUD or HADD to adsorbed FN, indicating that interactions involving type III modules more C-terminal than (FNIII)-F-3 limit beta-strand addition to 1-5FNI within intact soluble FN. Preincubation of FN with mAbIII-10 or heparin modestly increased binding to HADD or FUD. Thus, ligation of FNIII modules involved in binding of integrins and glycosaminoglycans, (FNIII)-F-10 and 12-14FNIII, increases accessibility of 1-5FNI. Allosteric loss of constraining interactions among 1-5FNI, (FNIII)-F-10, and 12-14FNIII likely enables assembly of FN into extracellular fibrils.