IGEM:MIT/2009/OfficialWiki

Introduction

Welcome to the 2009 MIT iGEM wiki. This is our 6th year in competition since the inaugural iGEM competition in 2004. In the year of 2006, MIT's team won Best Systems and received 3rd place in the Presentations category. In 2008, MIT received a gold medal for their iGEM project. Hopefully, in 2009, MIT will become a finalist and win the iGEM competition with their exciting project.

Summary

Biological switches are increasingly becoming a set of useful techniques. There are very few of these switches that are fast and reversible. Our project involves engineering baker's yeast, Saccharomyces cerevisiae, to be able to react to red and far-red light to be able to localize proteins to various points in the cell. This is done using the Phy-Pif system. Under exposure to red light, the proteins will begin to localize. Exposure to far red light will delocalize these proteins. This project has two components. One of these components involves metabolically engineering baker's yeast to be able to produce chromophores endogenously which are needed for this process to occur. The second part of this experiment is to localize portions of the Phy-Pif system to various points of the cell. Fluorescent proteins are used to observe the localization and delocalization of the proteins.

Introduction

The goal of the MIT iGEM 2009 team is to create a fast-reversible localization switch in baker's yeast, Saccharomyces cerevisiae, using light. A fast-reversible switch will have many different applications. With this system, one will be able to conduct diffusion studies much easier, as they can localize the protein to one part of the cell, and then allow it to delocalize and watch the diffusion patterns. This can also be applied to cell cycle synchronization, by moving essential proteins for cell growth to various points in the cell where they will become ineffective.

The system that will be used in these studies is the Phy-Pif system. The Phy-PIF system uses phytochromes, which are photoreceptors in plants that regulate plant development in response to different light signals. It involves the interaction between the phytochrome (Phy) and the phytochrome interacting factor (PIF) after receiving a light signal. The phytochrome is originally in a conformation where it can absorb red-light (around 660 nm), designated as the Pr conformation, which is the inactive conformation. Once this phytochrome absorbs the red light it changes conformation to another conformation that absorbs far red-light (around 730 nm), designated as the Pfr conformation which is the active conformation. Once the conformation has become active, the phytochrome interacts with the PIF protein.

The phytochrome is a protein complex with a chromophore, which in our case is phycocyanobilin (PCB).