Nudeotide sequence analysis of tbe trimethoprim resistant dihydrofolate reductase encoded by R plasmid R751

Flensburg, John; Steen, Rolf

doi:10.1093/nar/14.14.5933

Cited by 46 publications

(38 citation statements)

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“…All contain a similar but not identical 78-amino-acid sequence. The plasmid R388-encoded DHFR enzyme differs in 11 amino acids from the plasmid R751-encoded DHFR enzyme; the R388 and R67 enzymes differ in 17 amino acids; and the R67 and R751 enzymes differ in 17 amino acids (28,79,94). Although the molecular masses of the DHFR Ta and DHFR II enzymes are similar (Table 1), neither amino acid nor nucleotide sequence homology exists.…”

Section: Plasmid-mediated Tmp-resistant Dhfr Enzymesmentioning

confidence: 99%

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Trimethoprim resistance

Huovinen

1987

Antimicrob Agents Chemother

102

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Section: Plasmid-mediated Tmp-resistant Dhfr Enzymesmentioning

confidence: 99%

“…Although differences in amino acid sequences between DHFR II enzymes exist, for the enzymes encoded by plasmids R388 and R751, amino acids 22 to 78 are identical, and the R67 enzyme differs in only 6 amino acids in this region (28,77,79,94).…”

Section: Plasmid-mediated Tmp-resistant Dhfr Enzymesmentioning

confidence: 99%

Trimethoprim resistance

Huovinen

1987

Antimicrob Agents Chemother

102

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“…The trimethoprimresistant dihydrofolate reductases found in Gramnegative bacteria have been divided into a number of classes based principally on their biochemical profiles (for reviews see Amyes, 1989;Huovinen, 1987). In addition, as some of the genes responsible have also had their DNA nucleotides sequenced, the classification of these enzymes now also takes into account amino acid differences (Stone & Smith, 1979;Zolg & Hanggi, 1981 ;Fling & Richards, 1983;Flensburg & Steen, 1986;Fling et al, 1988;Sundstrom et al, 1988). Initially resistance…”

Section: Introductionmentioning

confidence: 99%

N-terminal amino acid sequence of the novel type IIIb trimethoprim-resistant plasmid-encoded dihydrofolate reductase from Shigella sonnei

Thomson

Barg

Amyes

1990

Journal of General Microbiology

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The type IIIb dihydrofolate reductase, a novel plasmid-encoded enzyme recently identified in Shigellu sonnei, has been shown to have some similar biochemical properties to the type IIIa dihydrofolate reductase which was first identified in New Zealand in 1979. However, the type IIIb enzyme has a Ki for trimethoprim of 0.4 p~, and a pl of 5-35 (as compared to 19 nM and 6.1 for the type IIIa); both these results suggest that it is a different enzyme from the prototype type IIIa. The type IIIb dihydrofolate reductase was purified by methotrexate agarose affinity chromatography, yielding a pure protein as determined by HPLC. Automatic amino acid analysis of the purified enzyme showed it to be distinct from all other known plasmid-encoded dihydrofolate reductases and quite different from the type IIIa enzyme. The purified enzyme was examined by SDS-PAGE, which revealed that the type IIIb dihydrofolate reductase was a monomeric protein of Mr 17200.

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“…Type II DHFRs form another supergroup of DHFRs even more homologous with one another but with a structure distinct from that of any other known DHFR (7,14,50,57).…”

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confidence: 99%