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. 2010 Mar 8;54(5):2125–2134. doi: 10.1128/AAC.01420-09

TABLE 3.

Effect of genes whose inactivation prevented repression of hdeAB by MarA on MarA-mediated MDR

Protein/function Gene Locusb Level of MarA-mediated MDR (% of parental level)a
FOX NOR CHL MIN
Transcriptional regulators
    Cold shock protein CspG cspGpc b0990 54 91 93 75
    Cyclic AMP receptor protein crp b3357 21 33 29 38
    DNA-binding protein H-NS hns b1237 19 23 20 35
    OmpR transcriptional dual regulator ompR b3405 67 77 93 100
Enzymes
    Acid phosphatase appA b0980 68 84 93 100
    Adenylate cyclase cyaA b3806 43 41 46 32
    Serine protease Do degP b0161 94 91 50 100
    Putative ring-cleavage enzyme of phenylacetate degradation maoC b1387 100 61 75 40
    Aspartate kinase/homoserine dehydrogenase metL b3940 120 91 100 100
    Poly(A) polymerase I; RNA modification pcnB b0143 10 23 33 30
    RecBCD DNA helicase/exonuclease recD b2819 80 77 50 65
    Trehalose-6-phosphate hydrolase treC b4239 94 46 85 100
    Oxidoreductase subunit paralog of DmsA ynfE b1587 94 68 93 100
Transport
    AcrAB-TolC multidrug efflux system acrA b0463 16 0 8 40
    AcrAB-TolC multidrug efflux system acrB b0462 6 9 8 40
    Putative propionic acid transporter mhpT b0353 68 91 100 100
    Subunit of nickel ABC transporter nikD b3479 68 68 50 125
    TolC outer membrane channel tolC b3035 0 0 0 40
Others
    Putative membrane protein alx b3088 120 68 100 65
    Predicted membrane-anchored protein damX b3388 40 46 50 30
    tRNA-methionine metV b2816 74 91 75 65
    CPS-53 (KpLE1) prophage; bactoprenol-linked glucose translocase (flippase) yfdG b2350 68 91 93 65
    Conserved protein yibLpc b3602 68 68 50 100
    Predicted unconserved protein yniDpc b4535 94 77 125 50
a

Abbreviations: FOX, cefoxitin; NOR, norfloxacin; CHL, chloramphenicol; MIN, minocycline. MarA-mediated MDR for each mutant was calculated as the fold increase in MIC for the ΔmarR background (CR1000-derivative mutant) compared to the MIC for the ΔmarRA background (CR2000-derivative mutant) by using the ΔmarR MIC/ΔmarRA MIC ratio. This ratio for the parental strains (the MIC for the ΔmarR parental strain CR1000 divided by the MIC for the ΔmarRA parental strain CR2000) for each antibiotic (shown in Table 2, footnote b) was considered to represent 100% MarA-mediated antibiotic resistance, whereas a ratio of 1 (with the MIC for the ΔmarR background being equal to the MIC for the ΔmarRA background) was considered to represent 0% MarA-mediated antibiotic resistance. These two reference points were used to calculate the percentage of MarA-mediated antibiotic resistance for each mutant according to its ΔmarR MIC/ΔmarRA MIC ratio. When inactivation of a gene significantly reduced MarA-mediated resistance to an antibiotic compared to the level for the parental strain (P < 0.01, associated with reductions of 50% or more), the corresponding value is highlighted in bold. For parental strains, n = 9; for mutants, n = 2 to 5.

b

The locus tags refer to accession numbers (http://biocyc.org/ecocyc/index.shtml).

c

The insertion of the transposome was in the promoter of the gene. All the other insertions were within the open reading frame (ORF) of the genes.