Phosphorylation-dependent conformational changes induce a switch in the actin-binding function of MARCKS
Phosphorylation-dependent conformational changes induce a switch in the actin-binding function of MARCKS
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DOI：
10.1074/jbc.274.51.36472
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发表时间：
1999-12-17
影响因子：
4.8
通讯作者：
Edison, AS
中科院分区：
文献类型：
--
作者：
Bubb, MR;Lenox, RH;Edison, AS
蛋白激酶 C 磷酸化富含肉豆蔻酰化丙氨酸的蛋白激酶 C 底物 (MARCKS)，消除了肌动蛋白丝交联活性，但残余的丝状结合活性将磷酸化的 MARCKS 停靠在丝状肌动蛋白上。 MARCKS 假定的肌动蛋白结合区域包括 Ca2+-钙调蛋白结合位点，已被描绘成具有 α 螺旋结构，类似于其他钙调蛋白结合域。先前的推测表明，MARCKS 可能二聚化，形成交联活性所需的两个功能性肌动蛋白结合位点。与这些假设相反，我们发现具有肌动蛋白交联活性的 MARCKS 肽在水溶液中具有延伸的结构，但在磷酸化后呈现出更紧凑的结构。我们假设磷酸化诱导的 MARCKS 肽的结构变化产生了一种动态结构，该结构平均只有一个肌动蛋白结合位点。此外，与磷酸化状态无关，该肽是单体而不是二聚体，这意味着两个不同的肌动蛋白结合位点负责未磷酸化的 MARCKS 的肌动蛋白交联活性。这些研究独特地阐明了 MARCKS 磷酸化诱导结构变化的机制，并表明这些结构变化如何决定生物活性。
Phosphorylation of myristoylated alanine-rich protein kinase C substrate (MARCKS) by protein kinase C eliminates actin filament cross-linking activity, but residual filament binding activity docks phosphorylated MARCKS on filamentous actin. The postulated actin-binding region of MARCKS, which includes a Ca2+-calmodulin-binding site, has been portrayed with alpha-helical structure, analogous to other calmodulin-binding domains. Previous speculation suggested that MARCKS may dimerize to form the two functional actin-binding sites requisite for cross-linking activity. Contrary to these hypotheses, we show that MARCKS peptide with actin-cross-linking activity has an extended structure in aqueous solution but assumes a more compact structure upon phosphorylation. We hypothesize that structural changes in the MARCKS peptide induced by phosphorylation create a dynamic structure that, on average, has only one actin-binding site. Moreover, independent of the state of phosphorylation, this peptide is monomeric rather than dimeric, implying that two distinct actin-binding sites are responsible for the actin-crosslinking activity of unphosphorylated MARCKS. These studies uniquely elucidate the mechanism by which phosphorylation of MARCKS induces structural changes and suggest how these structural changes determine biological activity.