LuxT controls specific quorum-sensing-regulated behaviors in Vibrionaceae spp. via repression of qrr1, encoding a small regulatory RNA

Abstract

Quorum sensing (QS) is a process of chemical communication bacteria use to transition between individual and collective behaviors. QS depends on the production, release, and synchronous response to signaling molecules called autoinducers (AIs). The marine bacterium Vibrio harveyi monitors AIs using a signal transduction pathway that relies on five small regulatory RNAs (called Qrr1-5) that post-transcriptionally control target genes. Curiously, the small RNAs largely function redundantly making it difficult to understand the necessity for five of them. Here, we identify LuxT as a transcriptional repressor of qrr1. LuxT does not regulate qrr2-5, demonstrating that qrr genes can be independently controlled to drive unique downstream QS gene expression patterns. LuxT reinforces its control over the same genes it regulates indirectly via repression of qrr1, through a second transcriptional control mechanism. Genes dually regulated by LuxT specify public goods including an aerolysin-type pore-forming toxin. Phylogenetic analyses reveal that LuxT is conserved among Vibrionaceae and sequence comparisons predict that LuxT represses qrr1 in additional species. The present findings reveal that the QS regulatory RNAs can carry out both shared and unique functions to endow bacteria with plasticity in their output behaviors.

Secreted Proteases Control the Timing of Aggregative Community Formation in Vibrio cholerae

“…S7A and B ). Similar to V. cholerae , other vibrios produce proteases in the HCD QS state ( 24 , 25 ). Further work may uncover whether V. harveyi , and perhaps other vibrios, uses a protease-dependent strategy analogous to that of V. cholerae to control the onset timing of multicellular community formation.…”

Fis Connects Two Sensory Pathways, Quorum Sensing and Surface Sensing, to Control Motility in Vibrio parahaemolyticus

“…The data also suggest that other factors are required to control qrr expression. For example, studies have shown that, AphA, LuxO, OpaR, and LuxT also significantly control qrr expression in Vibrio species ( Rutherford et al, 2011 ; Zhang et al, 2012 ; Kalburge et al, 2017 ; Eickhoff et al, 2021 ; Simpson et al, 2021 ).…”

Regulatory small RNA, Qrr2, is expressed independently of sigma factor-54 and functions autonomously inVibrio parahaemolyticusto control quorum sensing

“…We used Δ rpoN cell lysate grown to OD 0.5 and P qrr2 bait DNA. We identified a number of candidate regulators previously shown to bind to the qrr sRNA regulatory regions in V. harveyi (27, 34, 51) ( Fig. S10 and S11 ).…”