C. Levesque et al., DIVERSITY AND RELATIVE STRENGTH OF TANDEM PROMOTERS FOR THE ANTIBIOTIC-RESISTANCE GENES OF SEVERAL INTEGRONS, Gene, 142(1), 1994, pp. 49-54
The integron is a new type of mobile element containing one or more an
tibiotic-resistance-encoding genes site-specifically integrated as cas
settes. The integrated genes are expressed from a common promoter regi
on located in an adjacent conserved segment. Sequence analysis has rev
ealed the existence of four versions of the integron promoters. In thi
s study, we have determined the relative strength of the different int
egron promoters and compared their activity with that of the tac promo
ter. Each version of the promoter was cloned upstream from a promoter-
less chloramphenicol acetyltransferase-encoding gene (cat) in plasmid
pKK232-8. CAT activity was used to measure transcriptional expression
from the promoters of the antibiotic-resistance operon. The strongest
promoter is the Version (TTGACAN(17)TAAACT) found in plasmid R388 and
in transposon Tn1696. This promoter is six times more efficient than t
he derepressed tac promoter.