McClean: Working with the LoxP/Cre System in S. cerevisiae
The loxP/Cre recombinase system is an extremely powerful tool for genetic manipulation, allowing for conditional and site-specific integrations, excisions, and inversions, either in vivo or in vitro.
The loxP element is a 34 bp element, consisting of an 8bp region that confers directionality, flanked by 13 bp palindromic regions. The orientation of pairs of loxP sites determines the recombination outcome upon exposure to Cre recombinase. DNA in between loxP sites in opposing orientation is inverted while that in between sites facing the same direction is excised as a DNA circle, leaving a single loxP site, or "scar." Further, a pair of DNA molecules, at least one circular, each with a single loxP site, can be fused.
Using loxP/Cre in vivo with Yeast
A common use for the system in yeast is excising a selectable marker previously integrated into the genome. In our instance, we would transform pMM296 (pSH65 Carter and Delneri, 2010) into the strain of interest, plate on YPG, and replica plate onto YPD + 150 μg/mL Zeocin the next day (If your marker is counterselective, you can alternatively select for it's loss instead.) After you confirm the excision, lose pMM296 with the Plasmid Loss Assay
Please feel free to post comments, questions, or improvements to this protocol. Happy to have your input!
- List troubleshooting tips here.
- You can also link to FAQs/tips provided by other sources such as the manufacturer or other websites.
- Anecdotal observations that might be of use to others can also be posted here.
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Gietz, R.D. and R.A. Woods. (2002) TRANSFORMATION OF YEAST BY THE Liac/SS CARRIER DNA/PEG METHOD. Methods in Enzymology 350: 87-96.
- Megan N McClean 14:01, 20 July 2011 (EDT)
or instead, discuss this protocol.