Noise reduction by diffusional dissipation in a minimal quorum sensing motif

Area of Science:

• Systems Biology
• Molecular Biology
• Microbial Ecology

Background:

• Cellular processes are affected by molecular noise, challenging biological network robustness.
• Intracellular noise regulation is well-studied, but cell-cell communication offers a complementary approach.
• Quorum sensing (QS) is a bacterial communication system involving diffusible signals.

Purpose of the Study:

• To investigate how cell-cell communication, specifically quorum sensing, regulates molecular noise in bacterial gene expression.
• To analyze the mechanisms by which QS contributes to robust cellular function.

Main Methods:

• Developed and analyzed a stochastic model of a minimal quorum sensing motif in Gram-negative bacteria.
• Investigated the role of signal diffusion and transcriptional regulator turnover in noise attenuation.

Main Results:

• Diffusion of the QS signal and fast turnover of its transcriptional regulator effectively attenuate low-frequency extrinsic noise.
• This noise reduction mechanism, termed "diffusional dissipation," is a general property of related regulatory motifs.
• An unstable transcriptional regulator is advantageous in QS systems for expressing costly public goods.

Conclusions:

• Quorum sensing employs "diffusional dissipation" to enhance gene expression robustness by reducing molecular noise.
• This mechanism highlights the importance of signal diffusion and rapid regulator turnover for cellular network stability.
• The findings suggest evolutionary advantages for unstable regulators in QS-mediated production of public goods.