Structure of the Plasminogen Kringle 4 Binding Calcium-Free Form of the C-Type Lectin-Like Domain of Tetranectin

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• 作者：Steen Nielbo ; Jens K. Thomsen ; Jonas H. Graversen ; Peter Holme Jensen ; Michael Etzerodt ; Flemming M. Poulsen ; and Hans Christian Th//pubs.acs.org/images/gifchars/oslash.gif" border="0">
• 刊名：Biochemistry
• 出版年：2004
• 出版时间：July 13, 2004
• 年：2004
• 卷：43
• 期：27
• 页码：8636 - 8643
• 全文大小：303K
• 年卷期：v.43,no.27(July 13, 2004)
• ISSN：1520-4995

文摘

Tetranectin is a homotrimeric protein containing a C-type lectin-like domain. This domain(TN3) can bind calcium, but in the absence of calcium, the domain binds a number of kringle-type proteinligands. Two of the calcium-coordinating residues are also critical for binding plasminogen kringle 4(K4). The structure of the calcium free-form of TN3 (apoTN3) has been determined by NMR. Comparedto the structure of the calcium-bound form of TN3 (holoTN3), the core region of secondary structuralelements is conserved, while large displacements occur in the loops involved in calcium or K4 binding.A conserved proline, which was found to be in the cis conformation in holoTN3, is in apoTN3predominantly in the trans conformation. Backbone dynamics indicate that, in apoTN3 especially, two ofthe three calcium-binding loops and two of the three K4-binding residues exhibit increased flexibility,whereas no such flexibility is observed in holoTN3. In the 20 best nuclear magnetic resonance structuresof apoTN3, the residues critical for K4 binding span a large conformational space. Together with therelaxation data, this indicates that the K4-ligand-binding site in apoTN3 is not preformed.