Reporter

Part:BBa_K177038:Design

Designed by: Anna Olchowik   Group: iGEM09_Warsaw   (2009-09-09)

Bistable switch 1 testing device


Assembly Compatibility:
  • 10
    COMPATIBLE WITH RFC[10]
  • 12
    COMPATIBLE WITH RFC[12]
  • 21
    INCOMPATIBLE WITH RFC[21]
    Illegal BglII site found at 3058
  • 23
    COMPATIBLE WITH RFC[23]
  • 25
    INCOMPATIBLE WITH RFC[25]
    Illegal AgeI site found at 3645
    Illegal AgeI site found at 3757
  • 1000
    INCOMPATIBLE WITH RFC[1000]
    Illegal BsaI.rc site found at 1614


Design Notes

The most important components of the switch are repressor proteins cI (denoted here as cIts, see explanation below) and lacI. The whole device is composed of two main parts:

LacI under control of 'cI lam' promoter

cI lam
R0051
B0032		lacI
C0012

and

cI under control of Plac promoter

LacI
R0010
B0032		cIts
K177050

How it works?

Because cI is repressor of 'cI lam' promoter and lacI is repressor of Plac promoter (denoted here as 'LacI') there are only two mutually exclusive states of the switch:

  • Plac promoter is active which leads to cI expression. CI binds to 'cI lam' promoter and represses it so no genes under this promoter are expressed.
  • 'cI lam' promoter is active which leads to LacI expression. LacI binds to Plac promoter and represses it.

According to this, state of the switch should be stable in time until some external stimulus is applied.

How to switch its state?

To set the state of the switch 0,1mM IPTG and high temperature (42oC) are used.

  • After addition of 0,1mM IPTG LacI gets inactivated and transcription from Plac starts. cI is expressed which leads to repression of 'cI lam' promoter.
  • Heating the bacteria in 42oC inactivates CI protein and starts expression from 'cI lam' promoter.

Source

References