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Smallest Plasmid Origin - 393bps?

Shin-ichiro HIRAGA shiraga4 at bio.sci.osaka-u.ac.jp
Sat Nov 4 00:44:45 EST 1995

In article <jpcd0-0311951820000001 at>, 
jpcd0 at mole.bio.cam.ac.uk (John Dixon) wrote:

>Hi all, I am after as small an origin as possible (for a plasmid rescue
>system). ColE1 seems to be 900 or so bps, we have some old vectors with
>pBR oris of 580bps, and I've just found a ref (Thomas et al Mol Gen Genet
>1981 1-16 that talks of oriRK2 a 393bp fragment but this requires trans
>acting factors to be present in the genome of the bacteria or on another
>compatible plasmid.
>Is this the smallest ori? Can anyone point me in the right direction for
>some newer refs?


Plasmids ColE2-P9 and closely related ColE plasmids, studied in our Lab, 
only require about 50 bp region as replication origin. Of course, they 
also require plasmid-defined trans-acting protein. Normally, they have 10 
to 15 copies in E. coli, however, some copy number mutants up tp about 100 
copy are also available.

If you are interested, please contact my boss,
   Tateo ITOH
   Department of Biology
   Faculty of Science
   Shinsyu University
   Nagano 390, Japan
(He has been moved.)

   Molecular and General Genetics Vol.215: p209-216 (1989)
   Jounal of Bacteriology Vol.176: p7233-7243 (1994)

Shin-ichiro Hiraga
Graduate Student
Laboratory of Genetics
Faculty of Science
Osaka University
Toyonaka, Osaka 560
shiraga4 at bio.sci.osaka-u.ac.jp

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