PMID:19547746

Citation	Greenfield, D, McEvoy, AL, Shroff, H, Crooks, GE, Wingreen, NS, Betzig, E and Liphardt, J (2009) Self-organization of the Escherichia coli chemotaxis network imaged with super-resolution light microscopy. PLoS Biol. 7:e1000137
Abstract	The Escherichia coli chemotaxis network is a model system for biological signal processing. In E. coli, transmembrane receptors responsible for signal transduction assemble into large clusters containing several thousand proteins. These sensory clusters have been observed at cell poles and future division sites. Despite extensive study, it remains unclear how chemotaxis clusters form, what controls cluster size and density, and how the cellular location of clusters is robustly maintained in growing and dividing cells. Here, we use photoactivated localization microscopy (PALM) to map the cellular locations of three proteins central to bacterial chemotaxis (the Tar receptor, CheY, and CheW) with a precision of 15 nm. We find that cluster sizes are approximately exponentially distributed, with no characteristic cluster size. One-third of Tar receptors are part of smaller lateral clusters and not of the large polar clusters. Analysis of the relative cellular locations of 1.1 million individual proteins (from 326 cells) suggests that clusters form via stochastic self-assembly. The super-resolution PALM maps of E. coli receptors support the notion that stochastic self-assembly can create and maintain approximately periodic structures in biological membranes, without direct cytoskeletal involvement or active transport.
Links	PubMed PMC2691949 Online version:10.1371/journal.pbio.1000137
Keywords	Bacterial Proteins/biosynthesis; Chemoreceptor Cells; Chemotaxis; Escherichia coli/cytology; Escherichia coli/metabolism; Escherichia coli Proteins/biosynthesis; Membrane Proteins/biosynthesis; Microscopy; Models, Biological; Receptors, Cell Surface/metabolism; Recombinant Fusion Proteins/biosynthesis; Signal Transduction; Stochastic Processes
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ECOLI:CHEW		GO:0051286: protein localization to plasma membrane	ECO:0000314:		P		Figure 3C. shows that large clusters of CheW chemotaxis protein predominately assemble at the cell poles of the cellular membrane.	complete CACAO 11102
ECOLI:CHEY		GO:0072659: protein localization to plasma membrane	ECO:0000314:		P		Figure 3F. shows predominant CheY chemotaxis protein localization to the cellular poles of the cell membrane.	complete CACAO 11103
ECOLI:MCP2		GO:0051286: cell tip	ECO:0000314:		C		Figure 2H. demonstrates that the largest clusters of the TAR chemotaxis proteins are predominately localized at the cell poles.	complete CACAO 11101

References

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