Disruption of chemoreceptor signalling arrays by high levels of CheW, the receptor–kinase coupling protein

Cardozo, Marcos J.; Massazza, Diego A.; Parkinson, John S.; Studdert, Claudia A.

doi:10.1111/j.1365-2958.2009.07032.x

Cited by 34 publications

(51 citation statements)

References 41 publications

(68 reference statements)

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“…4E). Thus, high levels of CheW could interfere with MCP trimer formation, as has been observed experimentally (9,42). Therefore, formation of a functional array in vivo likely requires a fine balance between the three components.…”

Section: Resultsmentioning

confidence: 99%

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

Li¹,

Morado

et al. 2012

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

184

339

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The chemoreceptors of Escherichia coli localize to the cell poles and form a highly ordered array in concert with the CheA kinase and the CheW coupling factor. However, a high-resolution structure of the array has been lacking, and the molecular basis of array assembly has thus remained elusive. Here, we use cryoelectron tomography of flagellated E. coli minicells to derive a 3D map of the intact array. Docking of high-resolution structures into the 3D map provides a model of the core signaling complex, in which a CheA/CheW dimer bridges two adjacent receptor trimers via multiple hydrophobic interactions. A further, hitherto unknown, hydrophobic interaction between CheW and the homologous P5 domain of CheA in an adjacent core complex connects the complexes into an extended array. This architecture provides a structural basis for array formation and could explain the high sensitivity and cooperativity of chemotaxis signaling in E. coli.

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Section: Resultsmentioning

confidence: 99%

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

Li¹,

Morado

et al. 2012

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

184

339

View full text Add to dashboard Cite

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“…mutagenesis (22)(23)(24). Interactions between chemoreceptors and CheW, as well as those between chemoreceptors and CheA, are important for controlling CheA kinase activity (23,25,26). Cytoplasmic chemoreceptors appear to participate in similar interactions based on observations of interactions between CheW, CheA, and the PIR within the Tm14 cytoplasmic chemoreceptor from Thermotoga maritima (26).…”

Section: Fig 2 Schematic Of Chemotaxis Signal Transduction Chemorecementioning

confidence: 99%

Internal Sense of Direction: Sensing and Signaling from Cytoplasmic Chemoreceptors

Collins

Lacal

Ottemann

2014

Microbiol Mol Biol Rev

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SUMMARY Chemoreceptors sense environmental signals and drive chemotactic responses in Bacteria and Archaea . There are two main classes of chemoreceptors: integral inner membrane and soluble cytoplasmic proteins. The latter were identified more recently than integral membrane chemoreceptors and have been studied much less thoroughly. These cytoplasmic chemoreceptors are the subject of this review. Our analysis determined that 14% of bacterial and 43% of archaeal chemoreceptors are cytoplasmic, based on currently sequenced genomes. Cytoplasmic chemoreceptors appear to share the same key structural features as integral membrane chemoreceptors, including the formations of homodimers, trimers of dimers, and 12-nm hexagonal arrays within the cell. Cytoplasmic chemoreceptors exhibit varied subcellular locations, with some localizing to the poles and others appearing both cytoplasmic and polar. Some cytoplasmic chemoreceptors adopt more exotic locations, including the formations of exclusively internal clusters or moving dynamic clusters that coalesce at points of contact with other cells. Cytoplasmic chemoreceptors presumably sense signals within the cytoplasm and bear diverse signal input domains that are mostly N terminal to the domain that defines chemoreceptors, the so-called MA domain. Similar to the case for transmembrane receptors, our analysis suggests that the most common signal input domain is the PAS (Per-Arnt-Sim) domain, but a variety of other N-terminal domains exist. It is also common, however, for cytoplasmic chemoreceptors to have C-terminal domains that may function for signal input. The most common of these is the recently identified chemoreceptor zinc binding (CZB) domain, found in 8% of all cytoplasmic chemoreceptors. The widespread nature and diverse signal input domains suggest that these chemoreceptors can monitor a variety of cytoplasmically based signals, most of which remain to be determined.

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“…Specifically, CheW is bound to CheA (a histidine protein kinase) and participates in its autophosphorylation, which leads to swarming activation (2). However, it is also known that the overexpression of CheW inhibits swarming (47) and that a precise quantitative association between the CheW and CheA proteins is required for this kind of cellular motility (12,56). Furthermore, CheW and RecA have been shown to interact in vivo in E. coli (1), and, as mentioned above, E. coli mutants defective in recA do not swarm (28).…”

Section: S Enterica Recao6869 Mutants Do Not Swarmmentioning

confidence: 99%

Overexpression of therecAGene Decreases Oral but Not Intraperitoneal Fitness ofSalmonella enterica

et al. 2010

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Transcription of the Salmonella enterica recA gene is negatively controlled by the LexA protein, the repressor of the SOS response. The introduction of a mutation (recAo6869) in the LexA binding site, in the promoter region of the S. enterica ATCC 14028 recA gene, allowed the analysis of the effect that RecA protein overproduction has on the fitness of this virulent strain. The fitness of orally but not intraperitoneally inoculated recAo6869 cells decreased dramatically. However, the SOS response of this mutant was induced normally, and there was no increase in the sensitivity of the strain toward DNA-damaging agents, bile salts, or alterations in pH. Nevertheless, S. enterica recAo6869 cells were unable to swarm and their capacity to cross the intestinal epithelium was significantly reduced. The swarming deficiency in recAo6869 cells is independent of the flagellar phase. Moreover, swimming activity of the recAo6869 strain was not diminished with respect to the wild type, indicating that the flagellar synthesis is not affected by RecA protein overproduction. In contrast, swarming was recovered in a recAo6869 derivative that overproduced CheW, a protein known to be essential for this function. These data demonstrate that an equilibrium between the intracellular concentrations of RecA and CheW is necessary for swarming in S. enterica. Our results are the first to point out that the SOS response plays a critical role in the prevention of DNA damage by abolishing bacterial swarming in the presence of a genotoxic compound.In bacteria, RecA is a key protein in homologous recombination, enabling the alignment of DNA molecules prior to strand exchange (17). RecA is also the positive regulator of the SOS response, one of the most-well-studied DNA repair systems in bacteria (54). In Escherichia coli and other Enterobacteriaceae, the cellular SOS network consists of more than 40 genes whose products act together to ensure cell survival after DNA damage (25). The negative regulator of the SOS system, LexA, binds to a specific sequence, the SOS box, which is located in the promoter region of the controlled genes (54). In Gammaproteobacteria, the SOS box is an imperfect palindrome, comprising the sequence CTGTN 8 ACAG (54) and varying among the different bacterial phyla (22).The induction pathway of the SOS response seems to be conserved in all bacteria in which this DNA repair system is found. The RecA protein is activated after binding to singlestranded DNA resulting from inhibition of chromosomal replication (48). In turn, the activated RecA triggers autocatalytic cleavage of the LexA repressor. In E. coli, this cleavage occurs in the Ala 84 -Gly 85 bond of the regulator (36) in a process mediated by the residues Ser 119 and Lys 156 . Autocleavage resembles that described for serine proteases (38), and it prevents the binding of LexA to its specific recognition motif in the promoter region of SOS genes.In addition to DNA repair genes, the SOS response involves lytic-cycle repressors of temperate bacteriophages (54). In so...

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Disruption of chemoreceptor signalling arrays by high levels of CheW, the receptor–kinase coupling protein

Cited by 34 publications

References 41 publications

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

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

Internal Sense of Direction: Sensing and Signaling from Cytoplasmic Chemoreceptors

Overexpression of therecAGene Decreases Oral but Not Intraperitoneal Fitness ofSalmonella enterica

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