Unconventional conjugal DNA transfer in mycobacteria.
Bacterial conjugation is an active process that results in unidirectional transfer of DNA from a donor to a recipient cell. Most transfer systems are plasmid-encoded and require proteins to act at a unique cis-acting site to initiate and complete DNA transfer. By contrast, the Mycobacterium smegmatis DNA transfer system is chromosomally encoded. Here we show that multiple cis-acting sequences present on the chromosome can mediate transfer of a non-mobilizable test plasmid. Moreover, unlike conventional plasmid transfer, recipient recombination functions are required to allow this plasmid, and derivatives of it, to re-circularize through a process similar to gap repair. Extended DNA homology with the recipient chromosome is required to facilitate repair, resulting in acquisition of recipient chromosomal DNA by the plasmid. Together, these results show that DNA transfer in M. smegmatis occurs by a mechanism different from that of prototypical plasmid transfer systems.
Wang
Jun
J
Division of Infectious Disease, Wadsworth Center, New York State Department of Health, Albany, New York 12201-2002, USA.
Parsons
Linda M
LM
Derbyshire
Keith M
KM
D002876:Chromosomes, Bacterial / Q000235:genetics; D003227:Conjugation, Genetic; D004269:DNA, Bacterial / Q000235:genetics*; D024881:Drug Resistance, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D008957:Models, Genetic; D008969:Molecular Sequence Data; D020102:Mycobacterium smegmatis / Q000235:genetics*; D010957:Plasmids / Q000235:genetics; D011995:Recombination, Genetic
D004269:DNA, Bacterial