New insights into bacterial chemoreceptor array structure and assembly from electron cryotomography.

Area of Science:

• Molecular and Cellular Biology
• Biophysics
• Bacterial Signaling

Background:

• Bacterial chemoreceptors form large, ordered arrays crucial for chemotaxis.
• The precise principles governing the assembly and architecture of these arrays remain largely unknown.

Purpose of the Study:

• To elucidate the fundamental principles of bacterial chemoreceptor array assembly and structure.
• To identify key molecular components and conditions influencing array formation.

Main Methods:

• In vitro reconstitution of chemoreceptor complexes.
• Imaging of cellular and reconstituted arrays.
• Investigation of the role of membrane and molecular crowding.
• Analysis of the influence of CheA and CheW proteins.

Main Results:

• Receptors consistently form trimers-of-dimers as a fundamental building block.
• Membrane is not essential for lattice formation; molecular crowding can substitute.
• CheA and CheW proteins form a 'superlattice' that dictates the hexagonal array structure.
• Coordinated gene expression appears vital for optimal array order and spacing.

Conclusions:

• Bacterial chemoreceptor array assembly is guided by specific protein interactions and environmental conditions.
• The trimers-of-dimers unit and the CheA/CheW superlattice are key determinants of array architecture.
• Understanding these principles offers insights into massive macromolecular complex assembly.