title: A single promoter inversion switches Photorhabdus between pathogenic and mutualistic states.
abstract: Microbial populations stochastically generate variants with strikingly different properties, such as virulence or avirulence and antibiotic tolerance or sensitivity. Photorhabdus luminescens bacteria have a variable life history in which they alternate between pathogens to a wide variety of insects and mutualists to their specific host nematodes. Here, we show that the P. luminescens pathogenic variant (P form) switches to a smaller-cell variant (M form) to initiate mutualism in host nematode intestines. A stochastic promoter inversion causes the switch between the two distinct forms. M-form cells are much smaller (one-seventh the volume), slower growing, and less bioluminescent than P-form cells; they are also avirulent and produce fewer secondary metabolites. Observations of form switching by individual cells in nematodes revealed that the M form persisted in maternal nematode intestines, were the first cells to colonize infective juvenile (IJ) offspring, and then switched to P form in the IJ intestine, which armed these nematodes for the next cycle of insect infection.
authors: Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA.
authors: Vishal S
authors: VS
authors: Somvanshi
authors: Rudolph E
authors: RE
authors: Sloup
authors: Jason M
authors: JM
authors: Crawford
authors: Alexander R
authors: AR
authors: Martin
authors: Anthony J
authors: AJ
authors: Heidt
authors: Kwi-suk
authors: KS
authors: Kim
authors: Jon
authors: J
authors: Clardy
authors: Todd A
authors: TA
authors: Ciche
mesh_terms: D000818:Animals; D036781:Fimbriae Proteins / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D016680:Genome, Bacterial; D007422:Intestines / Q000382:microbiology; D009036:Moths / Q000382:microbiology*; D009154:Mutation; D010641:Phenotype; D020637:Photorhabdus / Q000166:cytology / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity*; D011401:Promoter Regions, Genetic; D017172:Rhabditoidea / Q000382:microbiology*; D057345:Sequence Inversion; D013559:Symbiosis; D014774:Virulence / Q000235:genetics
chemical_list: D036781:Fimbriae Proteins