Team:PKU Beijing/Notebook/AND Gate 1/Input/LacI TetR 6

Notebook > AND Gate 1 > Input > Some interesting result from pLac-RFP

Some interesting result from pLac-RFP
Motivation: we want the low copy plasmid backbone pSB4A5, and we know that the strain JM 109 has lacQ on its F plasmid. We wonder if the lacI expressed from F plasmid can repress the pLac on the pSB4A5.

Parts:  J04450 (backbone is pSB4A5)

Resource: J04450: from Lin Min, Plasmid

2009.8.13
Transformation: Plasmid J04450, competent cells JM109 100uL, Smear to LB plate with Amp

2009.8.14
The colonies on the plate became a little red, after 24 hours. But compare to no RFP colonies, they are just a little brighter. The second picture is for comparison with no GFP colonies.



2009.8.16
Inducing: Transfer one colony into 5mL LB, when it grows to OD 0.4~0.6. Add some IPTG (1mM) to induce, and half without any IPTG, as a control. After 4 hours, the difference is obvious: The left one is control, the right one is induced.

Result & discussion
The result suggests that we can make use of the lacIQ on the F plasmid of JM 109, if the pLac is on a low copy plasmid (such as pSB4A5, copy number=5). The amount of lacI can largely repress the expression of pLac. So, maybe we can construct the AND gate only use pLac, without any other lacI on that plasmid.