Identification and cloning of the Type IIIa plasmidencoded dihydrofolate reductase gene from trimethoprim-resistant gram-negative bacteria isolated in Britain
‡Correspondence should be sent to Dr S. G. B. Amyes, Department of Bacteriology, The Medical School, University of Edinburgh, Teviot Place, Edinburgh EH8 9AG.
A clinical strain of Escherichia coli isolated in Nottinghamshire in 1980 was shown to harbour the type IIIa trimethoprim-resistant dihydrofolate reductase gene, previously identified on only one occasion, in New Zealand in 1979. The gene was identified by hybridisation with an 855-bp type III gene probe and its classification as a type IIIa dihydrofolate reductase was confirmed by detailed biochemical analysis of the enzyme product. The dihydrofolate reductase was identical in size and isoelectric point with the original type IIIa enzyme and shared similar inhibitory and kinetic profiles. The trimethoprim resistance gene was subsequently cloned and the type IIIa dihydrofolate reductase gene was localised to a 700-bp EcoRI-PstI fragment. This smaller fragment may prove to be a more specific DNA probe for the future identification of type IIIa dihydrofolate reductase genes.
JoynerS S,
FlingM E,
StoneD,
BaccanariD P. Characterisation of an R-plasmid dihydrofolate reductase with a monomeric structure. J Biol Chem1984; 259:5851–5856
YoungH-K,
AmyesS G B. A new mechanism of plasmid trimethoprim resistance : characterisation of an inducible dihydrofolate reductase. J Biol Chem1986; 261:2503–2505
FlingM E,
WaltonL,
ElwellL P. Monitoring of plasmidencoded, trimethoprim-resistant dihydrofolate reductase genes: detection of a new resistant enzyme. Antimicrob Agents Chemother1982; 22:882–888
BargN,
HutsonF,
AmyesS G B,
ThomsonC J,
WhartonM,
SchaffnerW. Two outbreaks of dysentery caused by antibiotic resistant Shigella sonnei (ARS) elaborating a type I11 dihydrofolate reductase (DHFR). Abstracts of the Annual Meeting of the American Society of Microbiology1988c-108
TownerK J,
VenningB M,
PinnP A. Occurrence of transposable trimethoprim resistance in clinical isolates of Escherichia coli devoid of self-transmissi ble resistance plasmids. Antimicrob Agents Chemother1982; 21:336–338
CarterG I,
TownerK J,
SlackR C B. Rapid detection of a specific trimethoprim resistance gene using a biotinylated DNA probe. J Antimicrob Chemother1987; 20:335–341
FlingM E,
RichardsC. The nucleotide sequence of the trimethoprim-resistant dihydrofolate reductase gene harbored by Tn7. Nucleic Acids Res1983; 11:5147–5158
ZolgJ W,
HanggiU J,
ZachauH G. Isolation of a small DNA fragment carrying the gene for dihydrofolate reductase from a trimethoprim resistance factor. MolGen Genet197; 164:15–29
TownerK J,
YoungH-K,
AmyesS G B.
Biotinylated DNA probes for trimethoprim-resistant dihydrofolate reductases types IV and V. J Antimicrob Chemother1988; 22:285–291
AmyesS G B,
SmithJ T. The purification and properties of the trimethoprim-resistant dihydrofolate reductase mediated by the R-factor, R388. Eur J Biochem1976; 61:597–603
BroadD F,
SmithJ T. Classification of trimethoprim resistant dihydrofolate reductase mediated by Rplasmids using isoelectric focusing. Eur J Bwchem1982; 125:617–622
Identification and cloning of the Type IIIa plasmidencoded dihydrofolate reductase gene from trimethoprim-resistant gram-negative bacteria isolated in Britain