Use of Escherichia coli Mutants to Evaluate Purines, Purine Nucleosides, and Analogues

AUTOR(ES)

Hill, Donald L.

RESUMO

Of 142 purines, purine nucleosides, and analogues tested for inhibition of growth of Escherichia coli B Hill, 45 were active. Of these, 27 were evaluated for inhibition of other E. coli lines, including those resistant to 6-thioguanine, 2-fluoroadenosine, 2,6-diaminopurine, or 6-mercaptopurine. Most toxic to the parent lines were 2-fluoroadenosine, 2-fluoroadenine, 2-fluoro-5′-deoxyadenosine, adenosine, 6-thioguanosine, 6-thioguanine, 6-mercaptopurine, 6-mercaptopurine ribonucleoside, 2-azaadenine, 2′-deoxyinosine, 6-N-aminoadenine, and inosine. Hypoxanthine was strongly inhibitory only to E. coli B Hill. Evidence regarding the substrate specificity of the three purine phosphoribosyltransferases was obtained by assaying for these enzymes in extracts of the various cell lines and by cross-resistance studies. The line selected for resistance to 6-thioguanine had low guanine phosphoribosyltransferase activity (guanosine monophosphate: pyrophosphate phosphoribosyltransferase, EC 2.4.2.8) and was deficient in activity for xanthine and 6-thioguanine. The lines selected for resistance to 2-fluoroadenosine and 2,6-diaminopurine were deficient in adenine phosphoribosyltransferase activity (adenosine monophosphate: pyrophosphate phosphoribosyltransferase, EC 2.4.2.7), and that selected for resistance to 6-mercaptopurine had low hypoxanthine phosphoribosyltransferase activity and undetectable activity with 6-mercaptopurine as a substrate. Purine, 6-methylpurine, 2-fluoroadenine, 2,6-diaminopurine, and 2-azaadenine were classified as adenine analogues; 6-mercaptopurine and 8-aza-2,6-diaminopurine, as hypoxanthine analogues; and 6-thioguanine and 2-amino-6-chloropurine, as analogues of guanine. The inhibition of bacterial growth by hypoxanthine, inosine, 2′-deoxyinosine, or adenosine was prevented by small amounts of thiamine or by relatively high concentrations of either cytidine or uridine. Cytidine also reversed the inhibition by some purine and purine ribonucleoside analogues. Orotate phosphoribosyltransferase (OMP: pyrophosphate phosphoribosyltransferase, EC 2.4.2.10), a possible site of action for these compounds, was not inhibited directly by the toxic agents.

Documentos Relacionados

• Fluoride ion catalyzed alkylation of purines, pyrimidines, nucleosides and nucleotides using alky halides.
• Regulation of Purine Hydroxylase and Xanthine Dehydrogenase from Clostridium purinolyticum in Response to Purines, Selenium, and Molybdenum
• Interconversion and uptake of nucleotides, nucleosides, and purine bases by the marine bacterium MB22.
• Mutation in the phosphoribosylpyrophosphate synthetase gene (prs) that results in simultaneous requirements for purine and pyrimidine nucleosides, nicotinamide nucleotide, histidine, and tryptophan in Escherichia coli.
• ANTAGONISMS BETWEEN PURINES AND PURINE ANALOGUES IN AUXOTROPHS OF SALMONELLA TYPHIMURIUM1