Wu H, Xu M Q, Liu X Q
Biochemistry Department, Dalhousie University, Halifax, Nova Scotia B3H 4H7, Canada.
Biochim Biophys Acta. 1998 Sep 8;1387(1-2):422-32. doi: 10.1016/s0167-4838(98)00157-5.
A 429 aa theoretical intein is encoded in the dnaB gene (DNA helicase) of the cyanobacterium Synechocystis sp. strain PCC6803. This intein is shown to be capable of protein splicing with or without its native exteins when tested in E. coli cells. A centrally located 275 amino acid sequence (residues 107-381) of this intein can be deleted without loss of the protein splicing activity, resulting in a functional mini-intein of 154 aa in size. Efficient in vivo protein trans-splicing was observed when this mini-intein was split into a 106 aa N-terminal fragment containing intein motifs A and B, and a 48 aa C-terminal fragment containing intein motifs F and G. These results indicate that the N- and C-terminal regions of the Ssp DnaB intein, whether covalently linked with each other or not, can come together through non-covalent interaction to form a protein splicing domain that is functionally sufficient and structurally independent from the centrally located endonuclease domain of the intein.
在蓝藻集胞藻PCC6803株的dnaB基因（DNA解旋酶）中编码了一种含429个氨基酸的理论内含肽。在大肠杆菌细胞中进行测试时，该内含肽无论有无其天然外显肽都显示出能够进行蛋白质剪接。该内含肽位于中央的275个氨基酸序列（第107 - 381位氨基酸残基）可以被删除而不丧失蛋白质剪接活性，从而产生一个大小为154个氨基酸的功能性微型内含肽。当这个微型内含肽被拆分成一个包含内含肽基序A和B的106个氨基酸的N端片段以及一个包含内含肽基序F和G的48个氨基酸的C端片段时，观察到了高效的体内蛋白质反式剪接。这些结果表明，集胞藻DnaB内含肽的N端和C端区域，无论它们是否彼此共价连接，都可以通过非共价相互作用聚集在一起，形成一个功能上足够且在结构上独立于内含肽中央内切酶结构域的蛋白质剪接结构域。
