TY - JOUR
T1 - Direct visualization of Escherichia coli chemotaxis receptor arrays using cryo-electron microscopy
AU - Zhang, Peijun
AU - Khursigara, Cezar M.
AU - Hartnell, Lisa M.
AU - Subramaniam, Sriram
PY - 2007/3/6
Y1 - 2007/3/6
N2 - Signal transduction in bacterial chemotaxis is initiated by the binding of extracellular ligands to a specialized family of methyl-accepting chemoreceptor proteins. Chemoreceptors cluster at distinct regions of the cell and form stable ternary complexes with the histidine autokinase CheA and the adapter protein CheW. Here we report the direct visualization and spatial organization of chemoreceptor arrays in intact Escherichia coli cells by using cryo-electron tomography and biochemical techniques. In wild-type cells, ternary complexes are arranged as an extended lattice, which may or may not be ordered, with significant variations in the size and specific location among cells in the same population. In the absence of CheA and CheW, chemoreceptors do not form observable clusters and are diffusely localized to the cell pole. At disproportionately high receptor levels, membrane invaginations containing nonfunctional, axially interacting receptor assemblies are formed. However, functional chemoreceptor arrays can be reestablished by increasing cellular levels of CheA and CheW. Our results demonstrate that chemotaxis in E. coli requires the presence of chemoreceptor arrays and that the formation of these arrays requires the scaffolding interactions of the signaling molecules CheA and CheW.
AB - Signal transduction in bacterial chemotaxis is initiated by the binding of extracellular ligands to a specialized family of methyl-accepting chemoreceptor proteins. Chemoreceptors cluster at distinct regions of the cell and form stable ternary complexes with the histidine autokinase CheA and the adapter protein CheW. Here we report the direct visualization and spatial organization of chemoreceptor arrays in intact Escherichia coli cells by using cryo-electron tomography and biochemical techniques. In wild-type cells, ternary complexes are arranged as an extended lattice, which may or may not be ordered, with significant variations in the size and specific location among cells in the same population. In the absence of CheA and CheW, chemoreceptors do not form observable clusters and are diffusely localized to the cell pole. At disproportionately high receptor levels, membrane invaginations containing nonfunctional, axially interacting receptor assemblies are formed. However, functional chemoreceptor arrays can be reestablished by increasing cellular levels of CheA and CheW. Our results demonstrate that chemotaxis in E. coli requires the presence of chemoreceptor arrays and that the formation of these arrays requires the scaffolding interactions of the signaling molecules CheA and CheW.
KW - Cryo-tomography
KW - Molecular architecture
KW - Signal transduction
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U2 - 10.1073/pnas.0610106104
DO - 10.1073/pnas.0610106104
M3 - Article
C2 - 17360429
AN - SCOPUS:34247261989
SN - 0027-8424
VL - 104
SP - 3777
EP - 3781
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 10
ER -