多种S1断裂内含肽的体内交叉反应

断裂内含肽含有两个独立分离的多肽片段(N端内含肽和C端内含肽)，它催化蛋白质反式剪接反应，在蛋白质研究与蛋白质工程中已得到诸多实际应用.在蛋白质反式剪接过程中，内含肽的N端内含肽和C端内含肽通过结构互补特异性地非共价组合.然而，Ssp DnaX S1型断裂内含肽的较大C端内含肽片段近来被发现能够与源自其它内含肽的N端内含肽片段交叉反应，表明蛋白质内含子Ssp DnaX具有结构杂交特征.本研究对另外2种S1型内含肽Rma DnaB和Ssp GyrB的较大C端内含肽与不同S1型断裂内含肽的N 端内含肽交叉反应活性进行分析检测.目的是探讨S1型断裂内含肽的结构杂交特征是否具有普遍性.结果发现，Rma DnaB的S1 C端内含肽能够与Ssp GyrB的S1 N端内含肽交叉反应，却不能与Ssp DnaX的S1 N端内含肽交叉反应；与此相似，Ssp GyrB的S1 C端内含肽能够与Rma DnaB的 S1 N端内含肽交叉反应，却不能与Ssp DnaX的S1 N端内含肽交叉反应.此外，某些交叉反应表现出温度依赖性.这些结果对于内含肽的结构 功能关系以及S1型断裂内含肽的应用研究具有重要的意义.

In Vivo Cross-eactivity between Multiple S1 Split Inteins

Split inteins consist of two separate polypeptides (N-intein and C-intein) and catalyze a protein trans-splicing reaction, and have many practical applications in protein research and engineering. In protein trans splicing, the N intein and the C-intein assemble non-covalently and specifically through structural complementation. However, the large C-intein of Ssp DnaX S1 split intein was recently found to cross-react with putative N inteins derived from other inteins, indicating a structural promiscuity of the Ssp DnaX intein. Here we evaluated two additional C-inteins, Rma DnaB and Ssp GyrB S1 split inteins, for cross reactivity with N-inteins of different S1 split inteins, in order to determine whether S1 split inteins are generally promiscuous. We found that the C-intein of Rma DnaB S1 split intein could cross-react with the N-intein of Ssp GyrB S1 split intein, but not with the N-intein of Ssp DnaX S1 split intein. Similarly, the C-intein of Ssp GyrB S1 split intein could cross react with the N intein of Rma DnaB S1 split intein, but not with the N-intein of Ssp DnaX S1 split intein. Some of the cross-reactivities also showed a temperature-dependence. These findings have interesting implications on intein structure function and on applications of these S1 split inteins in developing intein-based technologies.