LacI Inducible System
In this system, the lac repressor (LacI) is controlled by a strong constitutive promoter, and is upstream of mtrB under the control of pLac, a LacI regulated promoter. In the default state, LacI is expressed, and inhibits transcription at pLac. Thus, in the default state, mtrB is not expressed. IPTG (an analog of allolactose) induces mtrB expression by binding to LacI, thereby preventing it from inhibiting transcription at pLac.
 BBa_K098984 with BioBrick Prefix and Suffix Induction Test for lacI System with GFP
We tested the IPTG inducibility of [http://partsregistry.org/wiki/index.php?title=Part:BBa_K098982 BBa_K098982] in E. coli. In this system, the repressor (LacI) is driven by a weak promoter.
Method
 Click for diagram of induction experimental method
Results
Induction of GFP expression was observed at both 2 and 4 hours after adding IPTG. Levels of GFP expression in uninduced samples, however, remained relatively the same throughout the 4 hours. Meanwhile, IPTG induction was not observed in either the negative control ([http://partsregistry.org/wiki/index.php?title=Part:BBa_K098981| BBa_K098981]) or the constitutive GFP control ([http://partsregistry.org/wiki/index.php?title=Part:BBa_K098991| BBa_K098991]).
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