Disease relevance of oprD

• Interplay of Efflux System, ampC, and oprD Expression in Carbapenem Resistance of Pseudomonas aeruginosa Clinical Isolates [1].
• Using the above-mentioned oligonucleotide, the oprD structural gene was cloned and expressed in Escherichia coli on a 2.1-kb Bam HI-KpnI fragment [2].

High impact information on oprD

• Overexpression in a susceptible wild type strain of the mutated CzsS protein, but not of the wild type form, resulted in decreased oprD and increased czcC expression [3].
• Resistance to beta-lactam and FQ was correlated with ampC and mexC gene expression levels, respectively, whereas imipenem resistance was attributable to decreased oprD expression [4].
• Diminished expression of oprD was present in all imipenem- and meropenem-resistant isolates but was not required for ertapenem resistance [1].
• The meropenem MICs for strains carrying the oprD genes from clinical isolates were four times lower than that for the strain carrying the wild-type oprD gene [5].
• To investigate the negative regulatory mechanisms influencing oprD expression, a gene upstream of the coregulated mexEF-oprN efflux operon, designated mexT, was cloned [6].

Chemical compound and disease context of oprD

• The effects of imipenem and meropenem on the transcriptional expression of resistance-related genes oprD, oprM and oprN in Pseudomonas aeruginosa were studied by quantitative real-time PCR [7].
• Effect of siliconized latex urinary catheters on the activity of carbapenems against Pseudomonas aeruginosa strains with defined mutations in ampC, oprD, and genes coding for efflux systems [8].

Biological context of oprD

• Restriction mapping and sequencing analysis of DNA from one representative plasmid from each group showed that both mutant oprD genes had a deletion [9].
• We observed a clear mosaicism in the results, non-congruence between results of different typing methods and a microscale mosaic structure in the oprD gene [10].
• In addition to the AFLP pattern and serotype, analysis of the nucleotide sequences of three (lipo)protein genes (oprI, oprL, and oprD) and the pyoverdine type revealed that all predominant strains except the SSD(r) strain belonged to recently identified clonal complexes [11].
• Loss of OprD production was likely due to oprD gene inactivation in both of cases, since the carbapenem-resistant isolates showed no cross resistance to levofloxacin and chloramphenicol compared with the carbapenem-susceptible isolates [12].
• However, this fragment did not contain the oprD structural gene as judged by its inability to hybridize with an oligonucleotide corresponding to the N-terminal amino acid sequence of OprD [2].

Associations of oprD with chemical compounds

• The addition of succinate exerted a negative effect on induction of oprD, likely due to catabolite repression [13].
• The arginine-mediated induction was dependent on the regulatory protein ArgR, and binding of purified ArgR to its operator upstream of the oprD gene was demonstrated by gel mobility shift and DNase assays [13].
• Next, in four ciprofloxacin-selected nfxC-like mutants, levels of oprD, oprM and oprN mRNA were compared with those of their wild-type counterparts [14].

Other interactions of oprD

• The level of oprN mRNA was significantly up-regulated, while the oprD gene was down-regulated (although this difference was statistically insignificant), in the mutants [14].
• This latter open reading frame, named opdE (for putative regulator of oprD expression), predicted a hydrophobic protein of M(r) 41,592 [2].
• Expression of mexEF-oprN is increased by five- to sixfold in PAODeltamvaT, while the expression of oprD is reduced by approximately twofold. mvaT mutation had no effect on the expression of other multidrug resistance operons, although it increased the expression of several ATP-binding cassette transporter genes [15].
• Iron transport profiles from myo-InsP6 into mutants lacking the outer membrane porins oprF, oprD and oprP were similar to the wild-type, indicating that these porins are not involved in the transport process [16].

Analytical, diagnostic and therapeutic context of oprD

• Northern blotting analysis showed that the gene with the 11-bp deletion was transcribed to about 1.5 kb of mRNA, but the gene with the large deletion produced undetectable RNA complementary to the oprD DNA probe [9].
• All these oprD/oprD (plasmid/chromosomal) mutants expressed undetectable levels of OprD2, as shown from an assay by the immunoblotting method [9].
• PCR was performed to amplify the oprD gene using primers upstream of the promoter and downstream of the structural gene [17].
• Sequence analysis indicated these inserts were novel insertion sequence elements transposed into different locations within oprD [17].
• Expression of oprD could only be detected in two of the strains, but expression was very low as indicated by the high number of RT-PCR cycles required to amplify the product [17].

References