Can I use pDONR201 and pDONR207 as Donor vectors?
pDONR201 and pDONR207 can be used, but they replicate less efficiently than the Donor vectors we offer, pDONR221 and pDONR/Zeo, even though both pDONR201 and pDONR207 contain the pUC ori. This results in lower plasmid yields. With pDONR221, plasmid yields are in the range of 0.5 - 1.0 µg of DNA per mL of culture.
Answer Id: 6800
What is the difference between your pDONR221 and pDONR/Zeo vectors?
How much DNA should I use in my BP reaction?
For the most efficient BP reaction, it is best to not have attB sites in molar excess of attP sites. The standard BP Reaction (20 µL) uses 300 ng (no more than 500 ng) of pDONR vector and 30-300 ng attB-flanked PCR product or Expression Clone for 1 hour at 25 degrees C. Using too much of the Donor vector in the reaction tube will inhibit the BP reaction and also result in intact donor vector being co-transformed with the Entry Clones. This will reduce the number of colonies on the plate by killing the transformed E. coli due to the presence of the ccdB gene. Longer incubation times of up to 24 hours can be used to convert a higher percentage of starting attB-DNA to product. For PCR products > 4 kb, the number of colonies obtained per fmol of PCR DNA added decreases with increasing size. Thus, for larger PCR products, it is recommended to increase the amount of DNA to at least 100 fmol of PCR product per 20 µL reaction, and using incubations longer than one hour (e.g., 6 hours or overnight to 24 hours). The largest PCR-amplified DNA cloned in-house was 10.1 kb. Increasing the incubation to 4-6 hours will typically increase colony output 2-3 fold and 16-24 hours will typically increase colony output 5-10 fold.
Answer Id: 6802
I forgot to add proteinase K to my BP reaction. Can I continue?
I performed a BP reaction and got few or no colonies after transformation, whereas the transformation control gave colonies. Can you please offer some suggestions?
Increase the incubation time up to 18 hours.
Make sure to treat reactions with proteinase K before transformation.
Check whether the correct antibiotic was used for selection.
Check whether the att site sequences are correct.
Check whether the correct Clonase® enzyme was used and whether it was functional.
Check whether the recommended amount of DNA was used in the reaction.
Check primer design and try gel/PEG purifying the attB-PCR product.
If the attB-PCR product or linear attB Expression clone is too long (>5 kb), incubate the BP reaction overnight.
Answer Id: 6845
I performed a BP reaction and got no colonies after transformation, and the recombination positive control was not successful. Can you please offer some suggestions?
I performed a BP reaction and got two distinct types of colonies (large and small) after transformation. What could be the possible reasons?
Plasmid was lost during culture due to large size or toxicity try incubating at 30 degrees C; use Stbl2 E.coli to stabilize the plasmid.
Deletions (full or partial) or point mutations in the ccdB gene obtain a new pDONR vector.
Answer Id: 6849
I performed a BP reaction and got high background after transformation. Can you please offer some troubleshooting tips?
Check whether the reaction was transformed into an E.coli strain containing the F' episome and the ccdA gene use an E.coli strain that does not contain the F' episome, e.g. OmniMAX™ 2-T1R, TOP10.
Deletion (full or partial) of the ccdB gene propagate in media with 50-100 mg/mL ampicillin and 15-30 µg/mL chloramphenicol.
Contamination from another resistant strain.
Check whether proper amount of DNA was used in the reaction.
Answer Id: 6851