title: Early stages in DNA binding and uptake during genetic transformation of pneumococci.
abstract: Ethylenediaminetetraacetate and other divalent-cation-complexing agents greatly stimulate the cellular binding of DNA molecules to competent pneumococci, while the appearance of genetic transformants and nuclease-resistant DNA binding are completely inhibited. Based on this finding, we developed an experimental system in which three early and consecutive stages of genetic transformation can be experimentally separated: (i) attachment of DNA molecules to cell surface sites that are only demonstrable in the competent state; (ii) a divalent-cation-dependent nucleolytic splitting and release of the adsorbed molecules to the medium; and (iii) emergence of potential transformants accompanied by an energy-requiring and divalent-cation-dependent process in which the cell-associated DNA molecules become inaccessible to shearing forces, nucleases, anti-DNA serum, and polycations.
mesh_terms: D001665:Binding Sites / Q000187:drug effects; D002118:Calcium; D002462:Cell Membrane / Q000378:metabolism; D002499:Centrifugation, Density Gradient; D004269:DNA, Bacterial / Q000032:analysis / Q000378:metabolism*; D003851:Deoxyribonucleases / Q000378:metabolism; D004492:Edetic Acid / Q000494:pharmacology; D008274:Magnesium; D013296:Streptococcus pneumoniae / Q000166:cytology / Q000378:metabolism*; D014170:Transformation, Genetic / Q000187:drug effects*; D014316:Tritium
chemical_list: D004269:DNA, Bacterial; D014316:Tritium; D004492:Edetic Acid; D003851:Deoxyribonucleases; D008274:Magnesium; D002118:Calcium