Question about pBR322 and pUC

[Liansen Liu]

Hi there,

Have you ever got any answer to your questions about the pUC and
pBR322 you posted in 1999? If so, could you please share them with me?

Thanks a lot.

Mark

I have a question reagarding the copy number of pBR322 based plasmids.
I have looked for references in the literature, but cannot find the
specific answer I seek.  I know that the main differences between pBR322
and pUC18 (with respect to replication and copy number) is that
pUC18 was created from pBR322 by deletion of the rop and mutatiion in the
ori.  From Current Protocols and Maniatis, I have found that the rop
is responsible for keeping the plasmid replication from going "nuts".
As a consequence, the copy number of pBR322 is ~10 copies per cell while
the copy number of pUC18 is ~700 copies per cell.  The mutation in the ori
is also a contributing factor in this higher copy number.  I would like
to know what the expected copy number would be of pBR322 WITHOUT the rop
but with no mutation in the ori?  I would expect that it would be much
greater than pBR322 but less than pUC18.  How much of a role does the
mutation in ori play?  Idea, answers, and references would be greatly
appreciated!!

Thanks!

Chuck Miller