Prophage excision activates Listeria competence genes that promote phagosomal escape and virulence.
The DNA uptake competence (Com) system of the intracellular bacterial pathogen Listeria monocytogenes is considered nonfunctional. There are no known conditions for DNA transformation, and the Com master activator gene, comK, is interrupted by a temperate prophage. Here, we show that the L. monocytogenes Com system is required during infection to promote bacterial escape from macrophage phagosomes in a manner that is independent of DNA uptake. Further, we find that regulation of the Com system relies on the formation of a functional comK gene via prophage excision. Prophage excision is specifically induced during intracellular growth, primarily within phagosomes, yet, in contrast to classic prophage induction, progeny virions are not produced. This study presents the characterization of an active prophage that serves as a genetic switch to modulate the virulence of its bacterial host in the course of infection.
Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Tel Aviv 69978, Israel.
Lev
L
Rabinovich
Nadejda
N
Sigal
Ilya
I
Borovok
Ran
R
Nir-Paz
Anat A
AA
Herskovits
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001435:Bacteriophages / Q000502:physiology*; D001483:Base Sequence; D002478:Cells, Cultured; D005260:Female; D008087:Listeria / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity* / Q000821:virology*; D008264:Macrophages / Q000166:cytology / Q000276:immunology* / Q000382:microbiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D010588:Phagosomes / Q000382:microbiology*; D016415:Sequence Alignment; D014775:Virus Activation
D001426:Bacterial Proteins