A conformational switch in the Piccolo C2A domain regulated by alternative splicing
A conformational switch in the Piccolo C2A domain regulated by alternative splicing
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DOI：
10.1038/nsmb707
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发表时间：
2004-01-01
影响因子：
16.8
通讯作者：
Rizo, J
中科院分区：
文献类型：
--
作者：
Garcia, J;Gerber, SH;Rizo, J
C-2 结构域是广泛存在的 Ca2+ 结合模块。活性区蛋白 Piccolo（也称为 Aczonin）包含一个不寻常的 C(2)A 结构域，该结构域对 Ca2+ 表现出低亲和力、Ca2+ 诱导的构象变化和 Ca2+ 依赖性二聚化。我们在此表明，通过选择性剪接去除九个残基序列会增加 Ca2+ 亲和力，消除构象变化并消除 Piccolo C(2)A 结构域的二聚化。无 Ca2+ 长变体的 NMR 结构为两种剪接形式的这些不同特性提供了结构基础，表明九残基序列形成了 β 链，否则被非剪接序列占据。因此，Ca2+ 与长 Piccolo C(2)A 结构域的结合需要二级结构的显着重排，而短变体则不会发生这种情况。这些结果揭示了 C-2 结构域的一种新的作用机制，并揭示了可能是通过短的选择性剪接序列改变蛋白质功能的结构原理。
C-2 domains are widespread Ca2+-binding modules. The active zone protein Piccolo ( also known as Aczonin) contains an unusual C(2)A domain that exhibits a low affinity for Ca2+, a Ca2+-induced conformational change and Ca2+-dependent dimerization. We show here that removal of a nine-residue sequence by alternative splicing increases the Ca2+ affinity, abolishes the conformational change and abrogates dimerization of the Piccolo C(2)A domain. The NMR structure of the Ca2+-free long variant provides a structural basis for these different properties of the two splice forms, showing that the nine-residue sequence forms a beta-strand otherwise occupied by a nonspliced sequence. Consequently, Ca2+-binding to the long Piccolo C(2)A domain requires a marked rearrangement of secondary structure that cannot occur for the short variant. These results reveal a novel mechanism of action of C-2 domains and uncover a structural principle that may underlie the alteration of protein function by short alternatively spliced sequences.