SURE vs. NovaBlue competent cells

John Brunstein brunstei at UNIXG.UBC.CA
Mon Mar 27 12:39:14 EST 1995


	SURE cells:
		e14-,del(mcrCB-hsdSMR-mrr)171, sbcC, recB, recJ, umuC::Tn5(
KanR), uvrC, supE44, lac, gyrA96, relA1, thi-1, endA1[F' proAB,
lacIq Z delM15, Tn10(TetR)]

	In other words, both Tn5 and Tn10 are present in this cell line.  
I routinely use it in the propagation of parvoviral genomic clones which 
contain 100-200 bp. GC-rich inverted repeat sequences without any 
problems, while in almost any other cell line our lab has observed almost 
immediate deletion of these sequences.  The strain grows quickly, gives 
good yields of clean plasmid in minipreps, and makes decent competent 
cells with the standard Ca++ protocalls.  The only problem I have 
encountered with this strain is that it is Dam+, thus some restriction 
sites (ie ClaI which I REALLY wanted to use) won't cut.
	Hope this answers your question.


On 27 Mar 1995, Malcolm Campbell wrote:

> 
> A little while back someone posted that Strategene's SURE cells harbour
> a Tn5 transposon.  Has anyone had any problems with these cells?  
> 
> We have been having problems with what looks like homologous recombination
> events with pBIN-based plasmids and with another group of plasmids which
> have an insert repeat.  To date we have been using Novagen's Novablue
> competent cells.  Has anyone has any problems with these cells?  
> 
> Our transformation efficiency is not really a problem.  It's just that we
> appear to be losing "chunks" between sequences that are repeated in the
> plasmids.  The NovaBlue cells are supposed to be recA1 mutants so I'm at
> a quandry as to what is going on.  My druthers at present are to switch to
> a massively recombination defficient strain like SURE; hoping that that
> may solve the problem.  Problem is I don't know anyone with experience
> with SURE cells.
> 
> Any advice for what should be routine subcloning experiments most appreciated.
> 
> Best regards,
> 
> Malcolm
> 
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