Promoter for Ampicillin in plasmids.

John Brunstein brunstei at UNIXG.UBC.CA
Sat Mar 26 17:39:46 EST 1994

	I have removed the SspI-SmaI fragment of pUC19 and recircularized
the vector without any apparent loss of b-lactamase expression as judged
by transformation efficiency; presumably therefore AmpR is expressed from
the lacZ promoter in this case.  In any event, this deletion derivative
has been an OK cloning vector in my hands by using AmpR as selectable
marker (obviously blue-white screening is out, however!).

On Fri, 25 Mar 1994, Bill Jack wrote:

> In article <1994Mar20.182857.1 at>, h9290184 at wrote:
>         >things deleted<
> > My question is would I be disabling the promoter used for the Amp. gene by 
> >  cutting with SspI?
> > I plan to do the same with a construct in pUC18 by removing the HindIII-SspI
> > fragment. From the reference I get from the NEB catalog page 158, the mature
> > beta-lactamase is from 2417 to 1629 while the SspI site is at 2501. I do think
> > that both plasmids share this same region if not more (from base 756 to 2686 by
> > fasta on linear sequences).
>  The -10 region on pUC19 is centered on nucleotide 2530, and the -35 at
> 2554. The start codon for the precursor of beta-lactamase is 2486 (the
> signal sequence is trimmed off). In short, SspI will separate the coding
> region from the promoter.

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