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- Title
The type VII dihydrofolate reductase: a novel plasmid-encoded trimethoprim-resistant enzyme from gram-negative bacteria isolated in Britain.
- Authors
Amyes, S. G. B.; Towner, K. J.; Carter, G. L.; Thomson, C. J.; Young, Hilary-Kay; Amyes, S G; Carter, G I; Young, H K
- Abstract
Plasmid pUN835 was identified in an Escherichia coli strain isolated from an outbreak of porcine diarrhoea on a farm near Nottingham, UK. The trimethoprim resistance gene did not hybridize with any of the gene probes derived from known plasmid-encoded trimethoprim resistance genes. The trimethoprim resistance gene of pUN835 was shown to encode the production of a dihydrofolate reductase which confers high-level resistance on its host. This enzyme was smaller than most plasmid-encoded dihydrofolate reductases (molecular mass = 11,500) and was labile to heat. It had relatively low affinity for the substrate dihydrofolate (Km = 20 microM) and it was resistant to competitive inhibition by trimethoprim (Ki = 7.0 microM). We classify this novel enzyme as type VII.
- Publication
Journal of Antimicrobial Chemotherapy (JAC), 1989, Vol 24, Issue 2, p111
- ISSN
0305-7453
- Publication type
journal article