Modification and functional inactivation of the tropoelastin carboxy-terminal domain in cross-linked elastin
Modification and functional inactivation of the tropoelastin carboxy-terminal domain in cross-linked elastin
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DOI：
10.1016/j.matbio.2008.06.001
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发表时间：
2008-09-01
期刊：
影响因子：
6.9
通讯作者：
Mecham, Robert P.
中科院分区：
文献类型：
--
作者：
Broekelmann, Thomas J.;Ciliberto, Christopher H.;Mecham, Robert P.
原弹性蛋白的羧基末端是分子的高度保守的非典型区域，其序列定义了细胞和基质相互作用。该结构域在弹性纤维成熟过程中原弹性蛋白的组装和交联中也起着关键但未知的作用。使用竞争性ELISA与弹性蛋白原的羧基末端的弹性蛋白酶抗性表位（域-36）的抗体，我们定量的水平的域-36序列的弹性蛋白酶衍生的肽从成熟的，不溶性的弹性蛋白。我们发现弹性蛋白中羧基末端表位的量类似于预期值的0.2%，假设掺入不溶性聚合物中的每个原弹性蛋白单体具有完整的羧基末端。低水平表明大多数结构域-36序列在弹性蛋白组装的某个阶段被去除，或者抗原表位被翻译后修饰改变。生化证据是一个潜在的赖氨酸衍生的交联在这个区域，这将改变羧基末端表位的可提取性和抗原性。这些结果表明，在成熟弹性蛋白中几乎没有或没有未修饰的结构域-36，表明随着弹性蛋白成熟，与弹性蛋白原的该区域相关的细胞和基质结合活性丧失或被修饰。结构域-36的交联功能可能有助于记录弹性蛋白中的多个交联位点，并解释了为什么改变结构域-36序列的突变对弹性纤维组装具有不利影响。(C)2008 Elsevier B.V保留所有权利。
The carboxy-terminus of tropoelastin is a highly conserved, atypical region of the molecule with sequences that define both cell and matrix interactions. This domain also plays a critical but unknown role in the assembly and crosslinking of tropoelastin during elastic fiber maturation. Using a competitive ELISA with an antibody to an elastase-resistant epitope in the carboxy-terminus of tropoelastin (domain-36), we quantified levels of the domain-36 sequence in elastase-derived peptides from mature, insoluble elastin. We found that the amount of carboxy-terminal epitope in elastin is similar to 0.2% of the expected value, assuming each tropoelastin monomer that is incorporated into the insoluble polymer has an intact carboxy-terminus. The low levels suggest that the majority of domain-36 sequence is either removed at some stage of elastin assembly or that the antigenic epitope is altered by posttranslational modification. Biochemical evidence is presented for a potential lysine-derived cross-link in this region, which would alter the extractability and antigenicity of the carboxy-terminal epitope. These results show that there is little or no unmodified domain-36 in mature elastin, indicating that the cell and matrix binding activities associated with this region of tropoelastin are lost or modified as elastin matures. A crosslinking function for domain-36 may serve to help register the multiple crosslinking sites in elastin and explains why mutations that alter the domain-36 sequence have detrimental effects on elastic fiber assembly. (C) 2008 Elsevier B.V All rights reserved.