QGEM’s 2014 project is titled “Inteins: Inspired by Nature, Accessible by Design.” Inteins are self-splicing amino acid sequences within host proteins that are able to excise themselves out auto-catalytically and ligate the flanking host protein sequences, or exteins. This relatively unknown technology has huge potential in the area of post-translational modification because of its speed and modularity. QGEM is working with inteins on two main levels to show their use as a foundation tool in synthetic biology, as well as a solution to a real world problem.
Project 1: Photo-intein
Unlike inteins that are found in nature, some inteins have separate C and N terminus domains that only splice when they are in close proximity to each other. These inteins are called trans-inteins. Our photo- intein project was inspired by the work of Tyszkiewicz and Muir in 2008; they created a light-activated protein splicing system using two chromoproteins, Phytochrome B (PhyB) and Phytochrome Associated Factor 3 (PIF3) and the VMA intein, naturally found in S. cerevisiae. After splitting the VMA intein, PhyB and PIF3 were attached to the C and N termini of the intein respectively. PhyB and PIF3, which associate when exposed to 660nm light, are able to bring the N and C termini of the intein together and initiate the splicing reaction. We aim to improve upon this with another intein, the NPU intein. The NPU intein, which is found in the cyanobacterium N. punctiforme, is up to 60x faster and may be able to speed the reaction time from 5 hours to 5 minutes. This reaction speed coupled with the ability to control the process with light can give researchers a valuable new tool to control protein expression at the post- translational level.![](https://static.igem.org/mediawiki/2014/6/6d/Project1.jpg)