Studying bacterial chemosensory array with CryoEM.

Zhuan Qin,Peijun Zhang

doi:10.1042/bst20210080

Abstract

Bacteria direct their movement in respond to gradients of nutrients and other stimuli in the environment through the chemosensory system. The behavior is mediated by chemosensory arrays that are made up of thousands of proteins to form an organized array near the cell pole. In this review, we briefly introduce the architecture and function of the chemosensory array and its core signaling unit. We describe the in vivo and in vitro systems that have been used for structural studies of chemosensory array by cryoEM, including reconstituted lipid nanodiscs, 2D lipid monolayer arrays, lysed bacterial ghosts, bacterial minicells and native bacteria cells. Lastly, we review recent advances in structural analysis of chemosensory arrays using state-of-the-art cryoEM and cryoET methodologies, focusing on the latest developments and insights with a perspective on current challenges and future directions.

Highlights

All motile bacteria and archaea examined to date possess a highly conserved chemosensory pathway that monitors the chemical environment and directs cell migration towards nutrient sources, a behavior known as chemotaxis [1,2,3,4,5]
Bacterial chemotaxis has served as a paradigmatic model for the study of cellular sensory signal transduction and motile behavior and plays an important role in infection and disease in a variety of human, animal, and plant pathogens [6]
We present an overview of systems employed for structural analysis of chemosensory arrays by cryo-electron microscopy (cryoEM) and cryo-electron tomography (cryoET) and review advances made during the past few years, highlighting some exciting cases where sub-nanometer resolution has been achieved and novel functional insights have been obtained

Summary

Introduction

All motile bacteria and archaea examined to date possess a highly conserved chemosensory pathway that monitors the chemical environment and directs cell migration towards nutrient sources, a behavior known as chemotaxis [1,2,3,4,5]. The structure and function of chemoreceptors and signaling arrays have been studied in a variety of systems (Table 1), including nanodiscs [7,15,16], lipid monolayer arrays [17,18], bacterial minicells [19,20], lysed bacterial ghosts [21,22] and intact native bacterial cells [1,20,23,24,25]. One strategy to reduce the sample thickness while keeping the membranes and chemosensory arrays intact is creating flattened bacterial ghost cells where most of the cytoplasm is released.

Results

Conclusion