Studies on the chemical nature and size of sex factors of Escherichia coli K12
1963; Elsevier BV; Volume: 6; Issue: 6 Linguagem: Inglês
10.1016/s0022-2836(63)80060-1
ISSN1089-8638
AutoresPatrice J. Driskell-Zamenhof, Edward A. Adelberg,
Tópico(s)Advanced biosensing and bioanalysis techniques
ResumoThe wild-type sex factor of Escherichia coli K12, F1, and a variant sex factor, F2, have been shown to be sensitive to decay of incorporated radiophosphorus. Labeled sex factors transferred into unlabeled recipient cells were observed to be subject to loss of function on storage; inactivation kinetics were described by concave exponential curves, indicating the transfer of only one sex factor particle to any one recipient. Mitomycin C was employed as a specific inhibitor of net DNA synthesis. A concentration of the antibiotic having no effect on net RNA or protein synthesis was found to inhibit incorporation of 32P into F1 particles and nuclei of F1 donor cells 64 and 69%, respectively, as determined by relative rates of 32P-decay inactivation of the genetic elements labeled in the presence and absence of mitomycin. An inhibition of incorporation of 32P into F2 and nuclei of donor cells of 68 and 64%, respectively, was observed. DNA is thus an essential constituent of the sex factors; RNA, in amounts detectable by the methods employed, is not. A comparison of the relative rates of 32P-decay inactivation of F1, F2, and bacteriophages T1 and T4 indicated that F1 comprises between 8·5 × 104 and 2·5 × 105 phosphorus atoms while F2 comprises between 1·9 × 105 and 5·4 × 105, upper limits being the more probable. This difference in size between the two sex factors was also demonstrated by the respective times required for transfer to recipients. The rate of sex factor transfer was estimated to be between 6·7 × 104 and 1·9 × 105 phosphorus atoms per minute.
Referência(s)