1887

Abstract

Six different R-factors conferring trimethoprim resistance had been isolated from a variety of sources. The trimethoprim-resistant dihydrofolate reductases (EC 1.5.1.3) from strains containing these R-factors were purified by ammonium sulphate precipitation and DEAE-cellulose ion-exchange chromatography. The enzymes showed no significant differences in molecular weight, pH profile, substrate profile, heat sensitivity, inhibition profile and Michaelis–Menten kinetics. There was, however, considerable variation in the specific activity of these enzymes in the same bacterial host. When two trimethoprimsensitive dihydrofolate reductases were examined as controls, considerable differences between their properties and those of the enzymes mediated by R-factors were detected. The data suggest that one trimethoprim resistance gene could be spreading through the bacterial population, possibly situated on a transposon.

Loading

Article metrics loading...

/content/journal/micro/10.1099/00221287-107-2-263
1978-08-01
2024-04-26
Loading full text...

Full text loading...

/deliver/fulltext/micro/107/2/mic-107-2-263.html?itemId=/content/journal/micro/10.1099/00221287-107-2-263&mimeType=html&fmt=ahah

References

  1. Amyes S. G. B., Smith J. T. 1974; R-factor trimethoprim resistance: an insusceptible target site. Biochemical and Biophysical Research Communications 58:412–418
    [Google Scholar]
  2. Amyes S. G. B., Smith J. T. 1976; The purification and properties of the trimethoprim-resistant dihydrofolate reductase mediated by the R-factor, R388. European Journal of Biochemistry 61:597–603
    [Google Scholar]
  3. Amyes S. G. B., Smith J. T. 1977; Trimethoprim resistance controlled by a combination of plasmid and chromosomal genes. Genetical Research 29:35–45
    [Google Scholar]
  4. Andrews P. 1964; Estimation of the molecular weight of proteins by Sephadex gel filtration. Biochemical Journal 91:222–233
    [Google Scholar]
  5. Barth P. T., Datta N. 1977; Transposons determining trimethoprim and streptomycin resistance that are indistinguishable from transposon 7. Proceedings of the Society for General Microbiology 499–100
    [Google Scholar]
  6. Barth P. T., Datta N., Hedges R. W., Grinter N. J. 1976; Transposition of a deoxyribonucleic acid sequence encoding trimethoprim and streptomycin resistance from R483 to other replicons. Journal of Bacteriology 125:800–810
    [Google Scholar]
  7. Breeze A. S., Sims P., Stacey K. A. 1975; Trimethoprim-resistant mutants of E. coli k12: preliminary genetic mapping. Genetical Research 25:207–214
    [Google Scholar]
  8. Burchall J. J., Hitchings G. H. 1965; Inhibitor binding analysis of dihydrofolate reductase from various species. Molecular Pharmacology 1:126–136
    [Google Scholar]
  9. Clowes R. C., Rowley D. 1954; Some observations on linkage effects in genetic recombination in Escherichia coli k12. Journal of General Microbiology 11:250–260
    [Google Scholar]
  10. Davis B. D., Mingioli E. S. 1950; Mutants of Escherichia coli requiring methionine or vitamin B12 . Journal of Bacteriology 60:17–28
    [Google Scholar]
  11. Dixon M., Webb E. C. 1958 Enzymes, 1.8–34 London: Longmans;
    [Google Scholar]
  12. Fleming M. P., Datta N., Gruneberg R. N. 1972; Trimethoprim resistance determined by R-factors. British Medical Journal i:726–728
    [Google Scholar]
  13. Hedges R. W., Jacob A. E. 1974; Transposition of ampicillin resistance from RP4 to other replicons. Molecular and General Genetics 132:31–40
    [Google Scholar]
  14. Hedges R. W., Datta N., Kontamichalou P., Smith J. T. 1974; Molecular specificities of R-factor-determined β-lactamases : correlation with plasmid compatibility. Journal of Bacteriology 117:56–62
    [Google Scholar]
  15. Jackson R. C., Harrap K. R. 1973; Studies with a mathematical model of folate metabolism. Archives of Biochemistry and Biophysics 158:827–841
    [Google Scholar]
  16. Matthews C. K., Sutherland K. E. 1965; Comparative biochemistry of bacterial and phage-induced dihydrofolate reductases. Journal of Biological Chemistry 240:2142–2147
    [Google Scholar]
  17. Osborn M. J., Huennekens F. M. 1958; Enzymic reduction of dihydrofolic acid. Journal of Biological Chemistry 233:969–974
    [Google Scholar]
  18. Shapiro J. A., Sporn P. 1977; Tn 402: a new transposable element determining trimethoprim resistance that inserts in bacteriophage Lambda. Journal of Bacteriology 129:1632–1635
    [Google Scholar]
  19. Waddell W. J. 1956; A simple ultraviolet spectro-photometric method for the determination of protein. Journal of Laboratory and Clinical Medicine 48:311–314
    [Google Scholar]
http://instance.metastore.ingenta.com/content/journal/micro/10.1099/00221287-107-2-263
Loading
/content/journal/micro/10.1099/00221287-107-2-263
Loading

Data & Media loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error