Cadherin adhesion depends on a salt bridge at the N-terminus
Cadherin adhesion depends on a salt bridge at the N-terminus
复制标题
DOI：
10.1242/jcs.02539
复制
发表时间：
2005-09-15
影响因子：
4
通讯作者：
Kilshaw, PJ
中科院分区：
文献类型：
--
作者：
Harrison, OJ;Corps, EM;Kilshaw, PJ
现在有相当多的证据表明，细胞粘附的钙粘蛋白需要一个链交换过程中，第二个氨基酸在N-末端的钙粘蛋白分子，色氨酸2，码头到一个疏水口袋中的结构域折叠的相对钙粘蛋白。在这里，我们表明，链交换依赖于一个钙粘蛋白分子的N-末端氨基和Glu 89的酸性侧链之间形成的盐桥。通过引入突变Glu 89 Ala或通过用额外的氨基酸延伸N-末端来防止N-钙粘蛋白中的这种键强烈抑制链交换。但当这两种修饰分别存在于相对的钙粘蛋白分子中时，它们以互补的方式起作用，降低了链交换的活化能，大大增加了粘附相互作用的强度。N-钙粘蛋白，保留一个未切割的前结构域或缺乏Trp 2坚持强烈的Glu 89 Ala突变体，但不野生型分子。类似地，其中疏水受体口袋被异亮氨酸侧链阻断的N-钙粘蛋白粘附到具有延长的N-末端的伴侣上。我们解释这些结果的自由能的变化，伴随着链交换。我们的研究结果为粘附机制提供了新的见解，并证明了大大增加钙粘蛋白亲和力的可行性。
There is now considerable evidence that cell adhesion by cadherins requires a strand exchange process in which the second amino acid at the N-terminus of the cadherin molecule, Trp2, docks into a hydrophobic pocket in the domain fold of the opposing cadherin. Here we show that strand exchange depends on a salt bridge formed between the N-terminal amino group of one cadherin molecule and the acidic side chain of Glu89 of the other. Prevention of this bond in N-cadherin by introducing the mutation Glu89Ala or by extending the N-terminus with additional amino acids strongly inhibited strand exchange. But when the two modifications were present in opposing cadherin molecules respectively, they acted in a complementary manner, lowering activation energy for strand exchange and greatly increasing the strength of the adhesive interaction. N-cadherin that retained an uncleaved prodomain or lacked Trp2 adhered strongly to the Glu89Ala mutant but not to wild-type molecules. Similarly, N-cadherin in which the hydrophobic acceptor pocket was blocked by an isoleucine side chain adhered to a partner that had an extended N-terminus. We explain these results in terms of the free energy changes that accompany strand exchange. Our findings provide new insight into the mechanism of adhesion and demonstrate the feasibility of greatly increasing cadherin affinity.