Molecular architecture of chemoreceptor arrays revealed by cryoelectron tomography of
            <i>Escherichia coli</i>
            minicells

Li, Jun; Hu, Bo; Morado, Dustin R.; Jani, Sneha; Manson, Michael D.; Margolin, William

doi:10.1073/pnas.1200781109

Cited by 187 publications

(369 citation statements)

References 66 publications

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“…1B), each CheA protomer contacts only one of the three dimers in the trimer of receptor dimers, and each CheW contacts a single, different dimer ( Fig. 1 C and D) (9,10). This suggested that only the dimer in direct physical contact with CheA P5 or alternatively only the dimer in direct contact with CheW had the ability to inhibit the kinase activity of the trimer-associated CheA protomer.…”

Section: Preparation Of Nanodiscs With Mixed Chemoreceptor Compositionsmentioning

confidence: 97%

“…Instead, we considered a model based on structure of the core complex that was determined experimentally by a combination of electron tomography and X-ray crystallography (9,10). In that structure, among the dimers in the receptor trimers of dimers there are dimer-specific contacts with CheA and with CheW.…”

Section: Preparation Of Nanodiscs With Mixed Chemoreceptor Compositionsmentioning

confidence: 99%

“…The minimal structural and functional core signaling complex contains two trimers of chemoreceptor homodimers, with each trimer in contact with a monomeric CheW and one of the two protomers in a CheA homodimer ( Fig. 1 C and D) (7)(8)(9)(10). Using Nanodiscs, individual core complexes can be reconstituted in vitro as water-soluble, active units (Fig.…”

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confidence: 99%

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Selective allosteric coupling in core chemotaxis signaling complexes

Hazelbauer

2014

Proc. Natl. Acad. Sci. U.S.A.

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Bacterial chemotaxis is mediated by signaling complexes that sense chemical gradients and direct bacteria to favorable environments by controlling a histidine kinase as a function of chemoreceptor ligand occupancy. Core signaling complexes contain two trimers of transmembrane chemoreceptor dimers, each trimer binding a coupling protein CheW and a protomer of the kinase dimer. Core complexes assemble into hexagons, and these form hexagonal arrays. The notable cooperativity and amplification in bacterial chemotaxis is thought to reflect allosteric interactions in cores, hexagons, and arrays, but little is known about this presumed allostery. We investigated allostery in core complexes assembled with two chemoreceptor species, each recognizing a different ligand. Chemoreceptors were inserted in Nanodiscs, which rendered them water soluble and allowed isolation of individual complexes. Neighboring dimers in receptor trimers influenced one another's operational ligand affinity, indicating allosteric coupling. However, this coupling did not include the key function of kinase inhibition. Our data indicated that only one receptor dimer could inhibit kinase as a function of ligand occupancy. This selective allosteric coupling corresponded with previously identified structural asymmetry: only one dimer in a trimer contacts kinase and only one CheW. We suggest one of these dimers couples ligand occupancy to kinase inhibition. Additionally, we found that kinase protomers are allosterically coupled, conveying inhibition across the dimer interface. Because kinase dimers connect core complex hexagons, allosteric communication across dimer interfaces provides a pathway for receptor-generated kinase inhibition in one hexagon to spread to another, providing a crucial step for the extensive amplification characteristic of chemotactic signaling.transmembrane receptors | bacterial chemotaxis | allosteric coupling | histidine kinases | Nanodiscs

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Section: Preparation Of Nanodiscs With Mixed Chemoreceptor Compositionsmentioning

confidence: 97%

Section: Preparation Of Nanodiscs With Mixed Chemoreceptor Compositionsmentioning

confidence: 99%

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Selective allosteric coupling in core chemotaxis signaling complexes

Hazelbauer

2014

Proc. Natl. Acad. Sci. U.S.A.

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“…Chemosensory proteins are found universally in large macromolecular clusters known as "chemotactic signaling arrays" (2)(3)(4)(5). MCPs, together with CheA and CheW, form the sensory core of these clusters.…”

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confidence: 99%

ParP prevents dissociation of CheA from chemotactic signaling arrays and tethers them to a polar anchor

Ringgaard

Zepeda-Rivera

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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Significance Targeting of cellular components to a particular site in a cell is often a highly regulated process, even in cells as small as bacteria. Robust chemotactic signaling, which is used by motile bacteria to survey their environments and navigate in response to them, requires appropriate cellular distribution of a large chemosensory apparatus. Here, we report how polarly flagellated vibrios ensure polar localization of their chemotactic machinery by capturing signaling proteins at the pole. Polar localization is mediated by a tripartite protein interaction network in which one protein prevents disassociation of a key signaling component from chemotactic complexes and tethers the complexes to a polar anchor. Polar tethering and localization are prerequisites for proper chemotaxis.

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“…As a result, species that generate thin cells, such as Rhodobacter sphaeroides and C. crescentus, make it possible to visualize protein complexes if they are sufficiently concentrated. E. coli and other larger rod-shaped cells are difficult to image because they are too thick, although tiny minicells of E. coli and other species have recently been exploited to visualize surface protein assemblies [88][89][90].…”

Section: Viewing Native Divisome Structures By Cryo-electron Tomographymentioning

confidence: 99%

The bacterial divisome: ready for its close-up

Rowlett

Margolin²

2015

Phil. Trans. R. Soc. B

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One contribution of 12 to a theme issue 'The bacterial cell envelope'. Bacterial cells divide by targeting a transmembrane protein machine to the division site and regulating its assembly and disassembly so that cytokinesis occurs at the correct time in the cell cycle. The structure and dynamics of this machine (divisome) in bacterial model systems are coming more clearly into focus, thanks to incisive cell biology methods in combination with biochemical and genetic approaches. The main conserved structural element of the machine is the tubulin homologue FtsZ, which assembles into a circumferential ring at the division site that is stabilized and anchored to the inner surface of the cytoplasmic membrane by FtsZ-binding proteins. Once this ring is in place, it recruits a series of transmembrane proteins that ultimately trigger cytokinesis. This review will survey the methods used to characterize the structure of the bacterial divisome, focusing mainly on the Escherichia coli model system, as well as the challenges that remain. These methods include recent super-resolution microscopy, cryo-electron tomography and synthetic reconstitution.

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Molecular architecture of chemoreceptor arrays revealed by cryoelectron tomography of Escherichia coli minicells

Cited by 187 publications

References 66 publications

Selective allosteric coupling in core chemotaxis signaling complexes

Selective allosteric coupling in core chemotaxis signaling complexes

ParP prevents dissociation of CheA from chemotactic signaling arrays and tethers them to a polar anchor

The bacterial divisome: ready for its close-up

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