Relative Strengths of Promoters Provided by Common Mobile Genetic Elements Associated with Resistance Gene Expression in Gram-Negative Bacteria

Comparison of green fluorescent protein expression from outward-facing promoters (P-OUT) of ISAba1, ISEcp1, and ISAba125 revealed approximate equivalence in strength, intermediate between PCS (strong) and PCWTGN-10 (weak) class 1 integron promoter variants, >30-fold stronger than P-OUT of ISCR1, and >5 times stronger than Ptac. Consistent with its usual role, PCWTGN-10 produces more mRNA from a downstream gfp gene transcriptionally linked to a usual PCWTGN-10-associated gene cassette than does P-OUT of ISAba1.