Acyl-homoserine lactones can induce virus production in lysogenic bacteria: an alternative paradigm for prophage induction.
Prophage typically are induced to a lytic cycle under stressful environmental conditions or when the host's survival is threatened. However, stress-independent, spontaneous induction also occurs in nature and may be cell density dependent, but the in vivo signal(s) that can trigger induction is unknown. In the present study, we report that acyl-homoserine lactones (AHL), the essential signaling molecules of quorum sensing in many gram-negative bacteria, can trigger phage production in soil and groundwater bacteria. This phenomenon also was operative in a lambda lysogen of Escherichia coli. In model coculture systems, we monitored the real-time AHL production from Pseudomonas aeruginosa PAO1 using an AHL bioluminescent sensor and demonstrated that lambda-prophage induction in E. coli was correlated with AHL production. As a working model in E. coli, we show that the induction responses of lambda with AHL remained unaffected when recA was deleted, suggesting that this mechanism does not involve an SOS response. In the same lambda lysogen we also demonstrated that sdiA, the AHL receptor, and rcsA, a positive transcriptional regulator of exopolysaccharide synthesis, are involved in the AHL-mediated induction process. These findings relate viral reproduction to chemical signals associated with high host cell abundance, suggesting an alternative paradigm for prophage induction.
Biosystems Engineering & Soil Science Department, University of Tennessee, Knoxville, Tennessee 37996, USA.
Dhritiman
D
Ghosh
Krishnakali
K
Roy
Kurt E
KE
Williamson
Sharath
S
Srinivasiah
K Eric
KE
Wommack
Mark
M
Radosevich
D054742:Acyl-Butyrolactones / Q000494:pharmacology*; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000821:virology*; D001426:Bacterial Proteins / Q000378:metabolism; D010582:Bacteriophage lambda / Q000187:drug effects / Q000254:growth & development; D001435:Bacteriophages / Q000187:drug effects* / Q000254:growth & development*; D004926:Escherichia coli / Q000235:genetics / Q000502:physiology / Q000821:virology; D029968:Escherichia coli Proteins / Q000378:metabolism; D008242:Lysogeny; D009154:Mutation / Q000235:genetics; D011550:Pseudomonas aeruginosa / Q000502:physiology / Q000821:virology; D012988:Soil Microbiology; D015534:Trans-Activators / Q000378:metabolism; D014775:Virus Activation; D014776:Virus Cultivation; D014871:Water Microbiology
D054742:Acyl-Butyrolactones; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C097686:SdiA protein, bacteria; D015534:Trans-Activators; C067572:RcsA protein, E coli