Department of Chemistry, College of the Holy Cross, Worcester, MA 01610, USA.
Biochem Biophys Res Commun. 2010 Dec 17;403(3-4):457-61. doi: 10.1016/j.bbrc.2010.11.055. Epub 2010 Nov 19.
Protein splicing is a post-translational process by which an intervening polypeptide, the intein, excises itself from the flanking polypeptides, the exteins, coupled to ligation of the exteins. The lon protease of Pyrococcus abyssi (Pab) is interrupted by an intein. When over-expressed as a fusion protein in Escherichia coli, the Pab lon protease intein can promote efficient protein splicing. Mutations that block individual steps of splicing generally do not lead to unproductive side reactions, suggesting that the intein tightly coordinates the splicing process. The intein can splice, although it has Lys in place of the highly conserved penultimate His, and mutants of the intein in the C-terminal region lead to the accumulation of stable branched-ester intermediate.
蛋白质剪接是一种翻译后过程，其中间多肽（即内含肽）从侧翼多肽（即外显肽）中切除自身，同时连接外显肽。Pyrococcus abyssi（Pab）的 lon 蛋白酶被内含肽打断。当作为融合蛋白在大肠杆菌中过表达时，Pab lon 蛋白酶内含肽可以促进有效的蛋白质剪接。阻断剪接各个步骤的突变通常不会导致无效的副反应，这表明内含肽严格协调剪接过程。尽管内含肽的倒数第二位残基是赖氨酸而不是高度保守的组氨酸，但它仍然可以剪接，并且内含肽 C 末端区域的突变会导致稳定的支链酯中间产物的积累。
