TABLE 1.
Relative expression levels of genes mexC, mexB, and mexY in clinical MexCD-OprJ-overproducing strainsa
| Strain (plasmid) | nfxB mutationb | Expressionc (fold change) of gene:
|
||||
|---|---|---|---|---|---|---|
| mexC | mexB |
mexY in strains
|
||||
| Uninduced | Induced withd:
|
|||||
| GEN | CHL | |||||
| PAO1 | None | 1 | 1 | 1 | 56.2 | 187.9 |
| EryR | C199Te | 43.3 | 1.4 | 6.4 | 53.5 | 129.3 |
| EryR(pNF225) | 4.8 | 1.1 | 4.5 | 65.3 | 185 | |
| 3308 | ΔA122-G131 | 38.4 | 0.4 | ≤0.1 | 0.2 | 1.1 |
| 3308(pNF225) | 6.3 | 0.6 | 0.1 | 0.5 | 0.6 | |
| 2439 | ΔG177-A178 | 32.4 | 0.8 | 2.0 | 20.3 | 129.8 |
| 2439(pNF225) | 7.8 | 0.7 | 0.4 | 19.3 | 117.4 | |
| 2126 | ΔC114-T130 | 74.9 | 0.9 | 1.1 | 10.6 | 101.8 |
| 2126(pNF225) | 10.4 | 0.9 | 0.5 | 16.2 | 81.6 | |
| 1956 | C113Tf | 21.6 | 0.4 | 0.8 | 15.5 | 103.2 |
| 1956(pNF225) | 6.4 | 0.2 | 0.7 | 33.5 | 122.4 | |
a
Control experiments showed that plasmid vector pMT45 had no influence on the RT-PCR results.
b
Nucleotide positions are numbered according to the PAO1 nfxB sequence.
c
Relative to the expression of uninduced strain PAO1 (which is assigned a value of 1). The presented values are means of three independent determinations.
d
Bacteria were cultivated for 4 h in the presence of gentamicin (GEN) or chloramphenicol (CHL) at one-half the MIC.
e
Nonsense mutation (Q67→amber stop).
f
Missense mutation Ala38→Val. This strain also contains the transitions G62A (Arg21→His) and A167G (Asp56→Gly), present in wild-type reference strain PA14 (http://v2.pseudomonas.com).