Lattice Ultrasensitivity Amplifies Signals in E. coli without Finely-Tuned Allosteric Interactions

Area of Science:

• Biochemistry
• Cellular Biology
• Systems Biology

Background:

• The *E. coli* chemosensory lattice is a key system for understanding biochemical signal processing.
• This lattice exhibits precise adaptation and high gain in response to ligand concentration changes.
• Existing models rely on allosteric interactions for signal gain.

Purpose of the Study:

• To introduce a novel model for the *E. coli* chemosensory lattice.
• To explain signal processing through a mechanism distinct from allosteric interactions.
• To account for experimental observations not explained by current models.

Main Methods:

• Development of a new lattice model termed lattice ultrasensitivity (LU).
• The model proposes that receptors gate enzymatic reactions between neighboring kinases.
• Analysis of gain mechanisms, focusing on timescale separation rather than allostery.

Main Results:

• The LU model achieves high gain through gating of far-from-equilibrium enzymatic reactions.
• Gain in the LU model is related to zero-order ultrasensitivity, not allostery.
• The model achieves arbitrarily high gain via timescale separation, avoiding fine-tuning.

Conclusions:

• The LU model provides an alternative mechanism for signal gain in the *E. coli* chemosensory lattice.
• This mechanism better explains certain experimental results compared to existing models.
• Potential implementations involve flexible linkers in the lattice's baseplate.