We're trying to clone various inserts into the pGAD424 vector from
Clontech. On several occasions, when we've transformed the resulting
ligations into various E. coli strains, we get weird smelling colonies
that we can't get the plasmids out of. We're pretty sure this isn't
contamination--it's pretty consistent with the inserts we're trying and
the negative control plates don't grow any colonies. We've seen this in
DH10B and XL-2 Blue strains. Also, we seem to be able to transform them
with the pGAD424 vector alone without any trouble.