Characterization of the Head-to-Tail Overlap Complexes Formed by Human Lamin A, B1 and B2 "Half-minflamin" Dimers
Characterization of the Head-to-Tail Overlap Complexes Formed by Human Lamin A, B1 and B2 "Half-minflamin" Dimers
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DOI：
10.1016/j.jmb.2009.12.001
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发表时间：
2010-02-26
影响因子：
5.6
通讯作者：
Herrmann, Harald
中科院分区：
文献类型：
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作者：
Kapinos, Larisa E.;Schumacher, Jens;Herrmann, Harald
半-minilibrium，代表氨基和羧基末端片段的人核纤层蛋白A，B1和B2与截短的中央杆域，研究其形成不同的头到尾型二聚体复合物的能力。这种相互作用模式代表了全长核纤层蛋白二聚体所表现出的纵向组装反应中的重要步骤。如通过分析超离心法所确定的，氨基末端片段在低离子强度条件下是可溶的，其沉降具有不同的曲线和S值（1.6-1.8 S），表明卷曲螺旋二聚体的形成。较小的羧基末端片段，除了核纤层蛋白B2，在这些条件下，很大程度上不溶。然而，在等摩尔量的同型氨基和羧基末端核纤层蛋白片段已混合在4 M尿素，在随后的复性后的羧基末端片段完全从沉淀和不同的可溶性复合物具有较高的S值（2.3-2.7 S）得到拯救。从这种行为，我们得出结论，氨基和羧基末端卷曲螺旋二聚体相互作用，形成不同的寡聚体（即四聚体）。此外，相应的相互作用之间也发生了异型对的A-和B-型核纤层蛋白片段。因此，A型核纤层蛋白二聚体可以与B型核纤层蛋白二聚体头对尾相互作用以产生线性聚合物。这些研究结果表明，核纤层蛋白二聚体主要具有与所有类型的核纤层蛋白的“组合”头-尾关联的自由，这一性质对于核纤层的组装可能具有重要意义。此外，我们认为，头到尾的杆端域的相互作用代表了一个主要步骤，在装配的细胞质中间丝蛋白。(C)2009爱思唯尔有限公司保留所有权利。
Half-minilamins, representing amino- and carboxy-terminal fragments of human lamins A, B1 and B2 with a truncated central rod domain, were investigated for their ability to form distinct head-to-tail-type dimer complexes. This mode of interaction represents an essential step in the longitudinal assembly reaction exhibited by full-length lamin dimers. As determined by analytical ultracentrifugation, the amino-terminal fragments were soluble under low ionic strength conditions sedimenting with distinct profiles and s-values (1.6-1.8 S) indicating the formation of coiled-coil dimers. The smaller carboxy-terminal fragments were, except for lamin B2, largely insoluble under these conditions. However, after equimolar amounts of homotypic amino- and carboxy-terminal lamin fragments had been mixed in 4 M urea, upon subsequent renaturation the carboxyterminal fragments were completely rescued from precipitation and distinct soluble complexes with higher s-values (2.3-2.7 S) were obtained. From this behavior, we conclude that the amino- and carboxy-terminal coiled-coil dimers interact to form distinct oligomers (i.e. tetramers). Furthermore, a corresponding interaction occurred also between heterotypic pairs of A- and B-type lamin fragments. Hence, A-type lamin dimers may interact with B-type lamin dimers head-to-tail to yield linear polymers. These findings indicate that a lamin dimer principally has the freedom for a "combinatorial" head-to-tail association with all types of lamins, a property that might be of significant importance for the assembly of the nuclear lamina. Furthermore, we suggest that the head-to-tail interaction of the rod end domains represents a principal step in the assembly of cytoplasmic intermediate filament proteins too. (C) 2009 Elsevier Ltd. All rights reserved.