Deciphering the Molecular Mechanism Underpinning Phage Arbitrium Communication Systems

Bacillus phages use a communication system, termed “arbitrium,” to coordinate lysis-lysogeny decisions. Arbitrium communication is mediated by the production and secretion of a hexapeptide (AimP) during lytic cycle. Once internalized, AimP reduces the expression of the negative regulator of lysogeny...

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Bibliographic Details
Published in:Molecular cell 2019-04, Vol.74 (1), p.59-72.e3
Main Authors: Gallego del Sol, Francisca, Penadés, José R., Marina, Alberto
Format: Article
Language:English
Subjects:
arbitrium system
Bacillus Phages - genetics
Bacillus Phages - metabolism
Bacillus subtilis - virology
decision-making
DNA - metabolism
Gene Expression Regulation, Viral
lysis
Lysogeny
Models, Molecular
phage communication
Protein Binding
Protein Interaction Domains and Motifs
protein plasticity
Protein Stability
quorum sensing
RRNPP
Signal Transduction
Structure-Activity Relationship
temperate phage
Viral Proteins - chemistry
Viral Proteins - genetics
Viral Proteins - metabolism
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Summary:Bacillus phages use a communication system, termed “arbitrium,” to coordinate lysis-lysogeny decisions. Arbitrium communication is mediated by the production and secretion of a hexapeptide (AimP) during lytic cycle. Once internalized, AimP reduces the expression of the negative regulator of lysogeny, AimX, by binding to the transcription factor, AimR, promoting lysogeny. We have elucidated the crystal structures of AimR from the Bacillus subtilis SPbeta phage in its apo form, bound to its DNA operator and in complex with AimP. AimR presents intrinsic plasticity, sharing structural features with the RRNPP quorum-sensing family. Remarkably, AimR binds to an unusual operator with a long spacer that interacts nonspecifically with the receptor TPR domain, while the HTH domain canonically recognizes two inverted repeats. AimP stabilizes a compact conformation of AimR that approximates the DNA-recognition helices, preventing AimR binding to the aimX promoter region. Our results establish the molecular basis of the arbitrium communication system. [Display omitted] •Crystal structures of AimR in its apo, AimP-, and DNA-bound states were determined•AimR belongs to the RRNPP family and presents high plasticity for DNA recognition•AimR operators present unusually long spacers recognized by the AimR TPR domain•AimP stabilizes a compact conformation of AimR, preventing operator recognition AimR is the sensor receptor of the arbitrium lysis-lysogeny decision system. Through structural and functional analyses, Gallego del Sol et al. reveal that intrinsic plasticity of AimR, which is restricted by the inhibitory AimP peptide, allows recognition of operators with unusually long spacers, deciphering the molecular basis of the arbitrium communication system.
ISSN:1097-2765
1097-4164
DOI:10.1016/j.molcel.2019.01.025