Open AccessDirectional transport and integration of donor DNA in Haemophilus influenzae transformation.
Author(s) -
Francis Barany,
Marc E. Kahn,
Hamilton O. Smith
Publication year - 1983
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.80.23.7274
Subject(s) - dna , haemophilus influenzae , plasmid , transformation (genetics) , circular bacterial chromosome , in vitro recombination , chemistry , homologous chromosome , microbiology and biotechnology , biophysics , biology , base pair , genetics , gene , molecular cloning , bacteria , peptide sequence
DNA transport and integration in Haemophilus influenzae transformation was studied with a plasmid clone of homologous DNA (pCML6). Our results indicate that: (i) donor DNA enters specialized membranous extensions on the cell surface, which we have termed "transformasomes"; (ii) linear DNA undergoes degradation upon exiting transformasomes; and (iii) DNA without a free end remains within transformasomes and is not degraded. By comparing the fate of label from uniformly labeled versus middle-labeled DNA, it appears that donor DNA undergoes degradation from an end prior to recombining with the chromosome. Using donor DNA with covalently closed termini (hairpin ends) prevents efficient exit from transformasomes. When one hairpin is removed, exit of donor DNA is shown to be directional from the free end, with preferential homologous integration of the 3' strand from that end.