[Entry of double-and single-stranded linear DNA in Ca2+-treated Escherichia coli cells]

Hydroxylapatite chromatography technique was used to investigate the conformational changes undergone by exogenous linear DNA during the uptake by Ca2+-treated EScherichia coli cells. Both single- (heat denatured) and double-stranded DNAs were examined. While native DNA preserved its double-strandedness during the uptake, the heat denatured (single-stranded) DNA was rapidly converted to the double-stranded form. This process was energy-dependent and is supposed to be dependent on gene recA product.