Phosphorylation and inactivation of kanamycin by Pseudomonas aeruginosa

Julian Davies and the discovery of kanamycin resistance transposon Tn5

This paper recounts some of my fond memories of a collaboration between Julian Davies and myself that started in 1974 in Geneva and that led to our serendipitous discovery of the bacterial kanamycin resistance transposon Tn5, and aspects of the lasting positive impact of our interaction and discovery on me and the community. Tn5 was one of the first antibiotic resistance transposons to be found. Its analysis over the ensuing decades provided valuable insights into mechanisms and control of transposition, and led to its use as a much-valued tool in diverse areas of molecular genetics, as also will be discussed here.

Phosphorylation of kanamycin, lividomycin A, amd butirosin B by Providencia stuartii

The isolation of Providencia stuartii resistant to multiple aminoglycoside antibiotics prompted an investigation into the mechanism of their resistance. Crude enzyme extracts of a strain of P. stuartii inactivated kanamycin, lividomycin A, and butirosin B in the presence of adenosine 5'-triphosphate (ATP), as measured by a microbiological assay. The occurrence of inhibitory concentrations of 500 mug or greater per ml against kanamycin, lividomycin A, and butirosin B, coupled with the inactivation of these antibiotics in the presence of ATP, suggested enzymatic phosphorylation. This was documented by the transfer of the gamma-phosphate of [gamma-(32)P]ATP. In contrast, the inability to inactivate gentamicin or tobramycin by the crude enzyme extracts in the presence of ATP suggests another enzymatic mechanism of resistance for these antibiotics, such as adenylation or acetylation. Of importance is the fact that amikacin, a semisynthetic analogue of kanamycin A which is resistant to inactivation by most resistance transfer factor enzymes, was found to inhibit the growth of P. stuartii at low concentrations.

Molecular characterization of the R factors implicated in the carbenicillin resistance of a sequence of Pseudomonas aeruginosa strains isolated from burns

An outbreak of R-factor-mediated carbenicillin resistance in Pseudomonas aeruginosa in burned patients in March 1969 was followed by a second outbreak 6 months later. No R-factor-carrying P. aeruginosa strains were detected in the intervening period but R-factor-determined lactamase was commonly encountered, particularly in Klebsiella aerogenes strains. A comparison of the molecular properties of the R factors in pseudomonads from the first and second phases with those in the Klebsiella strains from the intervening period showed them to be very closely related. A single R-factor type therefore may have been maintained in the Burns Unit between the two Pseudomonas outbreaks as a plasmid conferring resistance to ampicillin in K. aerogenes.

Phosphorylation of lividomycin by Escherichia coli carrying an R factor

A lividomycin-phosphorylating enzyme from a lividomycin-resistant strain of Escherichia coli carrying an R factor was partially purified by fractionation with ammonium sulfate and Sephadex G-100 column chromatography. The enzyme inactivated, in the presence of adenosine triphosphate and Mg(2+), several antibiotics having a d-ribose moiety linked to 2-deoxystreptamine, i.e., lividomycin A and B, neomycin, paromomycin, and vistamycin, but did not inactivate the kanamycins, streptomycin, or the gentamicin C components. Chemical studies of the inactivated product suggested that the phosphorylated site of the inactivated lividomycin was the hydroxyl group of the d-ribose moiety.

Antibacterial activity of lividomycin toward R factor-resistant strains of Escherichia coli

Forty-eight R factors conferring resistance to both kanamycin (KM) and streptomycin (SM) were demonstrated from 1,270 Escherichia coli strains of clinical origin. Among these R factors isolated, 42 also conferred resistance to the new antibiotic lividomycin (LV). Extracts of E. coli ML1410 carrying one such factor (R(M81)) inactivated LV as well as KM and SM. But extracts of E. coli ML1410 carrying an R factor (R(M82) or R(M83)) sensitive to LV could not inactivate LV. LV inactivation required both adenosinetriphosphate (ATP) and Mg(2+). Inactivated LV was reactivable by alkaline phosphatase. Isotopic studies with labeled ATP and elemental analysis of the reaction product indicate that it is a monophosphorylated derivative of LV.

Activity of lividomycin against Pseudomonas aeruginosa: its inactivation by phosphorylation induced by resistant strains

The antibacterial activity and enzymatic inactivation of lividomycin, a new aminoglycosidic antibiotic, were studied with 13 strains of Pseudomonas aeruginosa. The minimal inhibitory concentration of lividomycin was 12.5 to 25 mug/ml, and three strains were resistant to high concentrations of lividomycin (more than 200 mug/ml). It was found that P. aeruginosa TI-13 and K-11, highly lividomycin-resistant strains of clinical origin, strongly inactivated the drug. The third resistant strain, Km-41/R, was developed in vitro. Unlike the other resistant strains, Km-41/R, was developed in vitro. Unlike the other resistant strains, Km-41/R did not inactivate the drug, indicating that different mechanisms were involved in lividomycin resistance. By use of a cell-free extract from P. aeruginosa TI-13, the inactivation of lividomycin was found to be caused by the formation of a monophosphorylated product of the drug.