[Mechanism of conjugation in Escherichia coli K-12. IV. Conjugation in conditions of phenotypic suppression of gene dnaB mutation].

The thermosensitive mutation BT43 in the gene dnaB is a missence mutation affecting the vegetative and conjugational DNA synthesis. By means of the increase of ionic strength (NaCl concentration) in the medium the functional activity of the dnaB product is partially restored in non-permissive conditions. In these conditions a rescue of recombinant yield is observed. But the mechanism of recombination is switched from one-stranded to double-stranded. This is demonstrated by the alteration of the degree of linkage of genetically close markers.