Difference between revisions of "Part:BBa K750103"

Latest revision as of 01:11, 26 September 2012

PcIGLT:GFP(lva) repression system activated by cI protein

Description

This part contains promoter PcI, RBS of 1.0 strength, GFP(lva),double terminator. The GFP(lva) will be produced until the promoter Pci activated by protein cI. In the digital display part of our project, sometimes we need the cell can be swiched from light to dark. So we designed this part, and it can be used in number-switiching from 1 to 0 with another part BBa_K750000.

Performance

In our project, we utilized tubes with different kinds of bacteria as seven segments. According to the theory of network design, genetic logic gates were assembled into circuits and then constructed using synthetic biology method. Based on the knowledge of bioinformatics and synthetic biology, there are only two results for a single logic gate: on or off. Here, instead of electric signals representing streams of binary ones and zeros, the chemical concentrations of specific DNA-binding proteins and inducer molecules act as the input and output signals of the genetic logic gates, i.e. present or absent of a specific signal molecule represents binary one or zero. The genetic circuits we constructed actually using Binary-Coded Decimal (or BCD, a device which converts the binary numerical value to decimal value) to compute signal molecules.To display two results (in this case, number one and zero) necessitates one kind of signal molecule, we called it a Single-input BCD Decoder (As shown in Table 1).

Table 1. Design of circuits displaying the number 0 and 1. The inducer is arabinose, which effect on promoter PBAD (an E.coli promoter, see more[4]). In the absence of arabinose, cI regulated promoter(PcI) expresses GFP with LVA tag. In the presence of arabinose, PBAD starts transcription and then repressor CI protein is translated and represses PcI.

Table 2 presents the design of device displaying the number 0, 1, 2, which we called Dual-input BCD Decoder. Once the construction is completed, Engineered E.coli with different circuits can be immobilized into microcapsules and then be put in seven transparent tubes which acting as segment of display.

Table2.Biological digital display which responds to two inducers, displaying the number 0, 1, 2

Figure 1 presents the result obtained from fluorescent test on two circuits used in Single-input BCD Decoder. As can be seen from the graph, both two circuits function as expected. PciGLT (Part:BBa_K750103, short for PcI-rbs-gfp(LVA)-tt) continually expresses GFP while PBADGLT (Part:BBa_K750000) shows a significant up-and-down after adding arabinose.

Figure1.Fluorescent of two circuits for Single-input BCD Decoder

Sequence and Features