Direct Visualization of Horizontal Gene Transfer
Ana Babi
,1,2*
Ariel B. Lindner,1,2
Marin Vuli,1,2
Eric J. Stewart,1,2
Miroslav Radman1,2,3
Conjugation allows bacteria to acquire genes for antibiotic resistance, novel virulence attributes, and alternative metabolic pathways. Using a fluorescent protein fusion, SeqA-YFP, we have visualized this process in real time and in single cells of Escherichia coli. We found that the F pilus mediates DNA transfer at considerable cell-to-cell distances. Integration of transferred DNA by recombination occurred in up to 96% of recipients; in the remaining cells, the transferred DNA was fully degraded by the RecBCD helicase/nuclease. The acquired integrated DNA was tracked through successive replication rounds and was found to occasionally split and segregate with different chromosomes, leading to the inheritance of different gene clusters within the cell lineage. The incidence of DNA splitting corresponds to about one crossover per cell generation.
1 INSERM U571, Paris F-75015, France.
2 Université Paris Descartes Faculté de Médecine, Paris F-75015, France.
3 Mediterranean Institute for Life Sciences, Me
trovievo 
etalite bb, 21000 Split, Croatia.
* Present address: Unité Plasticité du Génome Bactérien, CNRS URA 2171, Institut Pasteur, 25 rue de Dr. Roux, Paris 75724, France.
Present address: Department of Biology, Northeastern University, 309 Mugar Hall, 360 Huntington Avenue, Boston, MA 02115, USA.
To whom correspondence should be addressed. E-mail: radman{at}necker.fr
