title: Effect of thymine-5-bromouracil substitution on F pili.
abstract: The effect of thymine-5-bromouracil substitution on the regeneration and length of F pili produced by an F(+)Lac(+)/Lac(-)Thy(-) strain of Escherichia coli was studied by electron microscopy. When 5-bromouracil (5BU) incorporation into deoxyribonucleic acid (DNA) was maximal, the modal length of the pilus doubled and the number of pili per cell was approximately 50% that of thymine-grown cells. The ability of 5BU-grown cells to form mating pairs and to be infected by ribonucleic acid (R17) and DNA (M13) male-specific phages was also reduced by approximately 50%. Loss of function was not due to loss of sex factor as 5BU cells retained a sex factor that was susceptible to curing by acridine orange. Elongation of pili on 5BU-grown cells was more sensitive to irradiation at 253.7 nm than on thymine-grown cells, suggesting that DNA is the sensitive target.
mesh_terms: D000166:Acridines / Q000494:pharmacology; D001976:Bromouracil / Q000378:metabolism*; D003090:Coliphages / Q000254:growth & development; D003227:Conjugation, Genetic; D003470:Culture Media; D004269:DNA, Bacterial / Q000096:biosynthesis / Q000528:radiation effects; D004926:Escherichia coli / Q000166:cytology* / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects; D008242:Lysogeny; D008854:Microscopy, Electron; D011830:Radiation Effects; D011995:Recombination, Genetic; D013941:Thymine / Q000378:metabolism; D014466:Ultraviolet Rays
chemical_list: D000166:Acridines; D003470:Culture Media; D004269:DNA, Bacterial; D001976:Bromouracil; D013941:Thymine