Stable Tandem Repeats?

Robert Whittier rfwhittier at hotmail.com
Tue Aug 21 20:01:34 EST 2001


As pointed out by Duncan Clark in a similar vein in this
month's thread on P1 lysogeny, you probably need to carry
out trial and error tests with a variety of host strains.
In my own limited experience, Stratagene's SURE cells were
marginally more stable for inverted repeats, but Life
Technologies' STABL2 were head-and-shoulders better for
a construct carrying several separated direct repeats. Your
mileage may vary. Both strains carry the gyrA96 mutation.
Presumably this reduces supercoiling, although I have to
admit ignorance whether this impacts the stability of direct
repeats in any way. Supercoiling can be expected to promote
chi structure formation in large palindromes. The centers
of these should look just like Holliday structures, and as
such are probably cleaved by the resolvases that normally
mediate the final steps of genetic recombination. The two
strains differ in that SURE attempts to knock down
recombinantion with recB and recJ, while STABL2 uses recA1.

Plasmid copy number and replicon types may also be major
factors for stability, although they were not critical in
my case.

Assuming that you overcome the problem, please post what
works back to this newsgroup.

I have no affiliation with either of the companies mentioned
above.

/Bob



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