Glycosylation Alters Dimerization Properties of a Cell-surface Signaling Protein, Carcinoembryonic Antigen-related Cell Adhesion Molecule 1 (CEACAM1)
Glycosylation Alters Dimerization Properties of a Cell-surface Signaling Protein, Carcinoembryonic Antigen-related Cell Adhesion Molecule 1 (CEACAM1)
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DOI：
10.1074/jbc.m116.740050
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发表时间：
2016-09-16
影响因子：
4.8
通讯作者：
Prestegard, James H.
中科院分区：
文献类型：
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作者：
Zhuo, You;Yang, Jeong-Yeh;Prestegard, James H.
人癌胚抗原相关细胞粘附分子1 (C？/Au: EACAM1)是一种参与细胞粘附、增殖和免疫应答的细胞表面信号分子。它还与癌症血管生成、进展和转移有关。这种不同的效应可能是由于CEACAM1与自身和其他分子之间的大量亲同性和亲异性相互作用而产生的。它的n端Ig变量（Ig(V)）结构域被认为是这些相互作用的主要参与者。以前的-三明治状Ig(V)结构域的晶体结构是使用大肠杆菌表达的材料产生的，这种材料缺乏天然糖基化。这些导致了二聚体界面的截然不同的建议，一种涉及ABED -链的相互作用，另一种涉及GFCCC -链，前者隐藏了一个突出的糖基化位点。这些结构提出了溶液中可能存在的形式以及糖基化对这种形式的影响的问题。在这里，我们使用核磁共振相互关联测量来检查糖基化对CEACAM1-Ig(V)二聚化的影响，并使用残余偶极偶联（RDC）测量来表征非糖基化形式的溶液结构。我们的研究结果表明，即使在潜在的糖基化位点添加单个n -连接的GlcNAc也会抑制二聚体的形成。令人惊讶的是，在大肠杆菌表达材料的溶液中收集的RDC数据表明，即使在没有糖基化的情况下，使用非糖基化GFCCC界面的二聚体也是首选的。这些结果开启了新的问题，即在体内还有哪些其他因素可能促进CEACAM1的二聚化，以及糖基化在异源性相互作用中可能发挥的作用。
Human carcinoembryonic antigen-related cell adhesion molecule 1 (C?/Au: EACAM1) is a cell-surface signaling molecule involved in cell adhesion, proliferation, and immune response. It is also implicated in cancer angiogenesis, progression, and metastasis. This diverse set of effects likely arises as a result of the numerous homophilic and heterophilic interactions that CEACAM1 can have with itself and other molecules. Its N-terminal Ig variable (Ig(V)) domain has been suggested to be a principal player in these interactions. Previous crystal structures of the -sandwich-like Ig(V) domain have been produced using Escherichia coli-expressed material, which lacks native glycosylation. These have led to distinctly different proposals for dimer interfaces, one involving interactions of ABED -strands and the other involving GFCCC -strands, with the former burying one prominent glycosylation site. These structures raise questions as to which form may exist in solution and what the effect of glycosylation may have on this form. Here, we use NMR cross-correlation measurements to examine the effect of glycosylation on CEACAM1-Ig(V) dimerization and use residual dipolar coupling (RDC) measurements to characterize the solution structure of the non-glycosylated form. Our findings demonstrate that even addition of a single N-linked GlcNAc at potential glycosylation sites inhibits dimer formation. Surprisingly, RDC data collected on E. coli expressed material in solution indicate that a dimer using the non-glycosylated GFCCC interface is preferred even in the absence of glycosylation. The results open new questions about what other factors may facilitate dimerization of CEACAM1 in vivo, and what roles glycosylation may play in heterophylic interactions.