Part:BBa_K2936029

LacI protain

This protein is the key protein in lactose operon，the product of lac I is called lac repressor. Its function is to bind to the 5'-terminal manipulating gene (lac O) of the target gene, which is located between the promoter (lac P) and the target gene. When repressors bind to manipulating genes, they block the initiation of transcription on promoters.

Contribution by MiamiU_OH

The function of the lac repressor is natively within E. coli, inhibiting transcription and creating a genetic switch out of the lac operon (1). The operon is diagrammatically depicted in the attached figure, the mechanism of which has been invaluable for genetic engineering by allowing user control of expression. In general, the operon is recognized by the lac repressor, the product of the LacI gene, which when bound cannot transcribe lacZ. This inhibition can be relieved by adding lactose or isopropyl-β-D-thiogalactoside (IPTG) to the culture.

Diagram of the operon model (1).

As explained in Messing, 1998, the lac operon is an excellent choice for genetic engineering in plant systems due minimization of plant promoter sequences, allowing control of the system even when implemented outside of the lab (2). Due to both this and the ease of use in lab, our team chose to regulate our overexpression plasmids via this operon. Our wet lab experiments also confirmed that this sequence is operational in Synechococcus elongatus PCC 7942, making the sequence a viable choice for future work in photosynthetic chassis organisms.

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  COMPATIBLE WITH RFC[21]
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  COMPATIBLE WITH RFC[1000]

References

1. Lewis, M. (2005). The lac repressor. Comptes Rendus Biologies, 328(6), 521-548. doi: 10.1016/j.crvi.2005.04.004 2. Messing, J. (1998). Plant science in lac: A continuation of using tools from Escherichia coli in studying gene function in heterologous systems. Proceedings Of The National Academy Of Sciences, 95(1), 93-94. doi: 10.1073/pnas.95.1.93