A Novel Structural Unit in the N-terminal Region of Filamins*
A Novel Structural Unit in the N-terminal Region of Filamins*
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DOI：
10.1074/jbc.m113.537456
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发表时间：
2014-01
期刊：
影响因子：
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通讯作者：
R. Sethi;Jonne Seppälä;H. Tossavainen;Mikko Ylilauri;S. Ruskamo;O. Pentikäinen;Ulla Pentikäinen;P. Permi;J. Ylänne
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文献类型：
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作者：
R. Sethi;Jonne Seppälä;H. Tossavainen;Mikko Ylilauri;S. Ruskamo;O. Pentikäinen;Ulla Pentikäinen;P. Permi;J. Ylänne
背景资料：丝状蛋白是肌动蛋白交联和信号支架蛋白，其中C-末端结构域具有结构域间相互作用，但对N-末端结构域知之甚少。结果：N-末端结构域3-5的晶体结构揭示了结构域4的新颖结构域包装和相互作用细节。结论：结构域4通过与结构域5的相互作用而稳定。意义：在这里，域间相互作用正调控域4与配体的相互作用。免疫球蛋白样（IG）结构域是一个广泛扩展的超家族，在多结构域蛋白中充当相互作用基序或结构间隔区。脊椎动物微丝蛋白（Vertebrate filthrin，FLN）是一种多功能肌动蛋白结合蛋白，由24个IG结构域组成。我们最近发现，在FLN的C-末端杆2区，IG结构域相互作用形成功能结构域对，其中与信号传导和跨膜蛋白的相互作用由弱肌动球蛋白收缩力机械调节。在这里，我们调查是否有类似的域间相互作用域4周围的N-末端杆1区域的FLN。蛋白质晶体结构揭示了结构域3、4和5之间的新型结构域组织。在这个模块中，域4和域5的交互相当紧密，而域3与域4具有部分灵活的接口。NMR肽滴定实验表明，在三结构域模块中，结构域4能够与来自血小板糖蛋白Ib的肽相互作用。与肽复合的FLN结构域4和5的晶体结构揭示了对于许多FLN配体观察到的典型β折叠增强相互作用。结构域5被发现稳定结构域4，这可以提供一种调节结构域4相互作用的机制。
Background: Filamins are actin cross-linking and signaling scaffolding proteins where C-terminal domains have inter-domain interactions but little is known about the N-terminal domains. Results: Crystal structures of N-terminal domains 3–5 reveal novel domain packing and interaction details of domain 4. Conclusion: Domain 4 is stabilized by interaction with domain 5. Significance: Here, inter-domain interactions positively regulate domain 4 interactions with ligands. Immunoglobulin-like (Ig) domains are a widely expanded superfamily that act as interaction motifs or as structural spacers in multidomain proteins. Vertebrate filamins (FLNs), which are multifunctional actin-binding proteins, consist of 24 Ig domains. We have recently discovered that in the C-terminal rod 2 region of FLN, Ig domains interact with each other forming functional domain pairs, where the interaction with signaling and transmembrane proteins is mechanically regulated by weak actomyosin contraction forces. Here, we investigated if there are similar inter-domain interactions around domain 4 in the N-terminal rod 1 region of FLN. Protein crystal structures revealed a new type of domain organization between domains 3, 4, and 5. In this module, domains 4 and 5 interact rather tightly, whereas domain 3 has a partially flexible interface with domain 4. NMR peptide titration experiments showed that within the three-domain module, domain 4 is capable for interaction with a peptide derived from platelet glycoprotein Ib. Crystal structures of FLN domains 4 and 5 in complex with the peptide revealed a typical β sheet augmentation interaction observed for many FLN ligands. Domain 5 was found to stabilize domain 4, and this could provide a mechanism for the regulation of domain 4 interactions.