lacU169(2nd attempt)

davesmith at davesmith at
Mon Oct 20 17:08:24 EST 1997

thomas=eitinger at (Thomas Eitinger) wrote:

>Unfortunately, I have not yet received a reply that really answers the
>question whether the lacU169 (lac-argF) deletion also comprises lacI or
>not. There are different statements in the catalogs. Life Technologies
>states that it covers lacZYA-argF whereas NEB defines it as
>lacIZYA-argF. Can anybody help to solve my problem, i.e. whether DH5
>alpha (lacU169) produces a Lac repressor from its chromosomal lacI gene
>or whether lacI is also deleted in lacU169 strains.


The lacU169 deletion is approx. 100,000 bp--since you can only get P1
to transduce it back to wild-type by the skin of your teeth.  And
since argF is duplicated in the genome (unless your strain is an
auxotroph for arginine because of some other deletion/mutation), you'd
have to conclude that ALL of the lac operon is gone.  No lacI
gene--that's my vote.

Hope this helps!

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