title: Mode of action of the competence-inducing factor of Bacillus stearothermophilus.
abstract: Development of competence in the noncompetent mutant of Bacillus stearothermophilus 4S requires a soluble competence-inducing factor (CF). This study describes several observations that define the mechanism of action of this factor. (i) CF interacts with cells, protoplasts, or cytoplasmic membranes in a temperature-dependent reaction; incubation of CF with cells alters the sedimentation properties of the cells. (ii) Association between CF and the cytoplasmic membrane appears to be the first and rate-limiting step in the process of transfection with deoxyribonucleic acid (DNA) from bacteriophage TP-IC. (iii) The membrane-CF complex is capable of removing infectious DNA from the supernatant fraction in vitro. (iv) Twenty phage-resistant mutants are unable to undergo the above reactions. A model is developed in which CF serves as a dynamic mediator of the reaction between the transfecting DNA and the cell surface.
mesh_terms: D000362:Agar; D000596:Amino Acids / Q000032:analysis; D000606:Amino Sugars / Q000032:analysis; D001407:Bacillus / Q000032:analysis / Q000254:growth & development*; D001435:Bacteriophages; D001665:Binding Sites; D002462:Cell Membrane / Q000032:analysis; D002499:Centrifugation, Density Gradient; D003470:Culture Media; D004279:DNA, Viral / Q000494:pharmacology*; D003851:Deoxyribonucleases / Q000494:pharmacology; D003973:Diatrizoate; D005827:Genetics, Microbial; D008858:Microscopy, Phase-Contrast; D008956:Models, Chemical; D009154:Mutation; D011523:Protoplasts / Q000032:analysis; D013696:Temperature; D014170:Transformation, Genetic; D014461:Ultracentrifugation
chemical_list: D000596:Amino Acids; D000606:Amino Sugars; D003470:Culture Media; D004279:DNA, Viral; D003973:Diatrizoate; D000362:Agar; D003851:Deoxyribonucleases