Wild-type pSC101 is about 5 copies/cell. It is compatible with both pUC19 and p15A. pCDF is also compatible with both, and has a copy number closer to your ideal range (10-50). pRSF -if memory serves- has a higher copy number, but is also compatible with both. Look for the manuals of the pDuet (sp?) vectors from Novagen, the info there will be useful.

By the way, if you can select independently for all three plasmids and maintaining copy number within a certain range is not that important, you can ignore ori compatibility. See e.g. PMID 17332010.

Hope it helps!

Thanks, Martin.

I am planning to co-express three different proteins in E. coli. I tried duet vector, containing two different genes, but it is too hard to maintain their expression level similarly.

As you said copy number of pCDF is 10-50, i will use pCDF vector with pUC19 and p15A. Your answer is verly helpful!

Thank you

You have to play with the strength of the translation initiation region (which spans not only the RBS but the region around it, including the 5' portion of the gene). Take a look at the RBS Calculator (google for it) and see if you can tweak it somehow.

Hi Soonbin, sorry to bother you. Do you still have the vector pCDFDuet1? May I ask for othe vector as I'm working on the co-expression? Thank you very much!

I'm sorry to respond too late, and i don't have pCDF because i decided to use pRSF vector. Anyway, good luck with the experiment.