Dormant phages communicate to control exit from lysogeny

Temperate bacterial viruses (phages) can transition between lysis - replicating and killing the host, and lysogeny - existing as dormant prophages while keeping the host viable. It was recently shown that upon invading a naïve cell, some phages communicate using a peptide signal, termed arbitrium, to control the decision of entering lysogeny. Whether communication can also serve to regulate exit from lysogeny (known as phage induction) remains unclear. Here we show that arbitrium-coding prophages continue to communicate from the lysogenic state by secreting and sensing the arbitrium signal. Signaling represses DNA-damage dependent phage induction, enabling prophages to reduce induction rate when surrounded by other lysogens. We show that the mechanism by which DNA damage and communication are integrated differs between distantly related arbitrium-coding phages. Additionally, signaling by prophages tilts the decision of nearby infecting phages towards lysogeny. Altogether, we find that phages use small molecule communication throughout their entire life-cycle to measure the abundance of lysogens in the population, thus avoiding wasteful attempts at secondary infections when they are unlikely to succeed.

Repeated outbreaks drive the evolution of bacteriophage communication

Recently, a small-molecule communication mechanism was discovered in a range of Bacillus-infecting bacteriophages, which these temperate phages use to inform their lysis-lysogeny decision. We present a mathematical model of the ecological and evolutionary dynamics of such viral communication, and show that a communication strategy in which phages use the lytic cycle early in an outbreak (when susceptible host cells are abundant) but switch to the lysogenic cycle later (when susceptible cells become scarce) is favoured over a bet-hedging strategy in which cells are lysogenised with constant probability. However, such phage communication can evolve only if phage-bacteria populations are regularly perturbed away from their equilibrium state, so that acute outbreaks of phage infections in pools of susceptible cells continue to occur. Our model then predicts the selection of phages that switch infection strategy when half of the available susceptible cells have been infected.

Two Cycling Centers in One Molecule: Communication by Through-Bond Interactions and Entanglement of the Unpaired Electrons

<div> <div> <div> <p>Many applications in quantum information science (QIS) rely on the ability to laser-cool molecules. The scope of applications can be expanded if laser-coolable molecules possess two or more cycling centers, i.e., moieties capable of scattering photons via multiple absorption-emission events. Here we employ equation-of-motion coupled-cluster method for double electron attachment (EOM-DEA-CCSD) to study electronic structure of hypermetallic molecules with two alkaline earth metals con- nected by an acetylene linker. We demonstrate that the interaction between two unpaired electrons is weak yet non-negligible, and is reflected in the underlying wavefunction. The electronic structure of the molecules is similar to that of two separated alkali metals, however the interaction between two electrons is largely dominated by through-bond interactions. The communication between the two cycling centers is quantified by the extent of the entanglement of the two unpaired electrons associated with each center. This contribution highlights rich electronic structure of hypermetallic molecules that may advance various applications in QIS and beyond. </p> </div> </div> </div>

Two Cycling Centers in One Molecule: Communication by Through-Bond Interactions and Entanglement of the Unpaired Electrons

<div> <div> <div> <p>Many applications in quantum information science (QIS) rely on the ability to laser-cool molecules. The scope of applications can be expanded if laser-coolable molecules possess two or more cycling centers, i.e., moieties capable of scattering photons via multiple absorption-emission events. Here we employ equation-of-motion coupled-cluster method for double electron attachment (EOM-DEA-CCSD) to study electronic structure of hypermetallic molecules with two alkaline earth metals con- nected by an acetylene linker. We demonstrate that the interaction between two unpaired electrons is weak yet non-negligible, and is reflected in the underlying wavefunction. The electronic structure of the molecules is similar to that of two separated alkali metals, however the interaction between two electrons is largely dominated by through-bond interactions. The communication between the two cycling centers is quantified by the extent of the entanglement of the two unpaired electrons associated with each center. This contribution highlights rich electronic structure of hypermetallic molecules that may advance various applications in QIS and beyond. </p> </div> </div> </div>