Phage-Encoded LuxR-Type Receptors Responsive to Host-Produced Bacterial Quorum-Sensing Autoinducers

Abstract

25Quorum sensing (QS) is a process of cell-to-cell communication that bacteria use to orchestrate 26 collective behaviors. QS relies on the cell-density-dependent production, accumulation, and 27 receptor-mediated detection of extracellular signaling molecules called autoinducers (AIs). Gram-28 negative bacteria commonly use N-acyl homoserine lactones (AHLs) as their AIs and they are 29 detected by LuxR-type receptors. Often, LuxR-type receptors are insoluble when not bound to a 30 cognate AI. In this report, we show that LuxR-type receptors are encoded on phage genomes 31 and, in the cases we tested, the phage LuxR-type receptors bind to and are solubilized specifically 32 by the AHL AI produced by the host bacterium. We do not yet know the viral activities that are 33 controlled by these phage QS receptors, however, our observations, coupled with recent reports, 34 suggest that their occurrence is more widespread than previously appreciated. Using receptor-35 mediated detection of QS AIs could enable phages to garner information concerning the 36 population density status of their bacterial hosts. We speculate that such information can be 37 exploited by phages to optimize the timing of execution of particular steps in viral infection. 38 39 Importance 40 Bacteria communicate with chemical signal molecules to regulate group behaviors in a process 41 called quorum sensing (QS). In this report, we find that genes encoding receptors for Gram-42 negative bacterial QS communication molecules are present on genomes of viruses that infect 43 these bacteria. These viruses are called phages. We show that two phage-encoded receptors, 44 like their bacterial counterparts, bind to the communication molecule produced by the host 45 bacterium, suggesting that phages can "listen in" on their bacterial hosts. Interfering with bacterial 46 QS and using phages to kill pathogenic bacteria represent attractive possibilities for development 47

New insights into intestinal phages

“…66 Finally, one has to mention the recent discovery of quorum-sensing pathways in phages of Enterococcus faecalis and Vibrio cholerae, suggesting that some prophages could regulate their induction rate in response to bacterial concentration. 67,68 Altogether, these results suggest that in the GIT, prophage induction might constitute a significant burden for their bacterial host, and alter microbiota composition. Indeed, it has been shown in mouse models that a high prophage induction rate modifies the equilibrium between bacterial strains by disfavoring lysogens.…”

Quorum Sensing Signals Alter in vitro Soil Virus Abundance and Bacterial Community Composition

“…The molecular basis of a host QS autoinducer controlling a phage lysogeny-lysis decision has been recently characterized (Silpe and Bassler, 2019a). Subsequent studies reported phage responses to other types of host autoinducers (Laganenka et al, 2019;Silpe and Bassler, 2019b). Bacteria communicate with their close relatives using specific QS signals, thus phage-bacterium QS connections may also be molecular structure dependent (Liang and Radosevich, 2019).…”

Dormant phages communicate to control exit from lysogeny

“…Many other phages are known to code for quorum-sensing systems or receptors with an unknown function (e.g. [38][39][40] ).…”