Team:SJTU-BioX-Shanghai/Project

Project: Condon Switch Controlling Protein Biosynthesis

Abstract

Protein Biosynthesis Controlling Elements

SJTU-BioX-Shanghai iGEM team is designing a modulating device that achieves fine tuning of target protein biosynthesis (translation).

The translation of the protein can be finely turned up/down with the control of the number of rare codons and the different strength of tRNA induction.

Besides, our device can be made into a real switch that can be turned on/off without background protein expression in two ways. One is to use any codon but initial codon to initiate translation, the other is to use stop codon as the controlling element.

Moreover, our design would be a brand-new way to selectively express part of a gene or introduce point mutations into target residues in proteins, thus favoring the study of the important domains or residues of a target protein.

Background

Gene expression regulation focuses mainly on two levels, one on transcription level and the other on translation level. The former is currently the mainstream. However, for transcription regulating tools such as lac operator and ara operator, protein biosynthesis cannot be finely tuned. Besides, background noise is nearly inevitable because of promoter leek.

Gene Expression Regulation Levels

Translational regulation exists widely in natural biological systems in various forms, including miRNA or siRNA directed gene silencing, mRNA degradation as well as riboswitch. Compared with transcriptional regulation, translational regulation is more direct and precise. Background noise can be eliminated under certain circumstances.

tRNA, a key element in translation, can act as a regulating tool. The abundance of tRNA is different in organisms. In natural biological systems, rare codons and the abundance of rare tRNA can regulate protein biosynthesis level. Based on this, we want to mimic and expand this phenomenon into a device that can regulate protein biosynthesis level with rare codons and rare tRNAs.

Introduction

Our project is divided into three sub-projects:Rare-Codon Switch, Stop-Codon Switch and Initial-Codon Switch.

• Rare-Codon Switch

Usage: a device that turns up/down protein translation

controlling elements: rare codon, rare codon recognizer tRNAs and engineered corresponding aminoacyl tRNA synthetases (aaRS)

• Stop-Codon Switch

Usage: a device that turns on/off protein translation

controlling elements: stop codon, stop codon recognizer tRNAs and engineered corresponding aaRS

• Initial-Codon Switch

Usage: a device that turns on/off protein translation

controlling elements: modified tRNA^Metand engineered methyl aminoacyl tRNA synthetase (MetRS)