Effect of loss of CheC and other adaptational proteins on chemotactic behaviour in Bacillus subtilis

Saulmon, Michael M.; Karatan, Ece; Ordal, George

doi:10.1099/mic.0.26463-0

Cited by 16 publications

(15 citation statements)

References 60 publications

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“…CheC was shown to have a dual role as a phosphatase for PϳCheY as well as in adaptation by interacting with CheB and affecting its activity on chemoreceptors in a methylation-independent process (33). CheC has also been proposed to bind directly to the switch of the flagellar motor and to affect the motility pattern (37). It is interesting to note that methylation-independent adaptation was previously shown to be important in chemotaxis in A. brasilense (39) and that the genome of A. brasilense encodes two CheC homologs (http://genome.ornl.gov/microbial/abra), whose function remains to be determined.…”

Section: Discussionmentioning

confidence: 99%

Function of a Chemotaxis-Like Signal Transduction Pathway in Modulating Motility, Cell Clumping, and Cell Length in the Alphaproteobacterium Azospirillum brasilense

Bible¹,

et al. 2008

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A chemotaxis signal transduction pathway (hereafter called Che1) has been previously identified in the alphaproteobacterium Azospirillum brasilense. Previous experiments have demonstrated that although mutants lacking CheB and/or CheR homologs from this pathway are defective in chemotaxis, a mutant in which the entire chemotaxis pathway has been mutated displayed a chemotaxis phenotype mostly similar to that of the parent strain, suggesting that the primary function of this Che1 pathway is not the control of motility behavior. Here, we report that mutants carrying defined mutations in the cheA1 (strain AB101) and the cheY1 (strain AB102) genes and a newly constructed mutant lacking the entire operon [⌬(cheA1-cheR1)::Cm] (strain AB103) were defective, but not null, for chemotaxis and aerotaxis and had a minor defect in swimming pattern. We found that mutations in genes of the Che1 pathway affected the cell length of actively growing cells but not their growth rate. Cells of a mutant lacking functional cheB1 and cheR1 genes (strain BS104) were significantly longer than wild-type cells, whereas cells of mutants impaired in the cheA1 or cheY1 genes, as well as a mutant lacking a functional Che1 pathway, were significantly shorter than wild-type cells. Both the modest chemotaxis defects and the observed differences in cell length could be complemented by expressing the wild-type genes from a plasmid. In addition, under conditions of high aeration, cells of mutants lacking functional cheA1 or cheY1 genes or the Che1 operon formed clumps due to cell-to-cell aggregation, whereas the mutant lacking functional CheB1 and CheR1 (BS104) clumped poorly, if at all. Further analysis suggested that the nature of the exopolysaccharide produced, rather than the amount, may be involved in this behavior. Interestingly, mutants that displayed clumping behavior (lacking cheA1 or cheY1 genes or the Che1 operon) also flocculated earlier and quantitatively more than the wild-type cells, whereas the mutant lacking both CheB1 and CheR1 was delayed in flocculation. We propose that the Che1 chemotaxis-like pathway modulates the cell length as well as clumping behavior, suggesting a link between these two processes. Our data are consistent with a model in which the function of the Che1 pathway in regulating these cellular functions directly affects flocculation, a cellular differentiation process initiated under conditions of nutritional imbalance.

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Section: Discussionmentioning

confidence: 99%

Function of a Chemotaxis-Like Signal Transduction Pathway in Modulating Motility, Cell Clumping, and Cell Length in the Alphaproteobacterium Azospirillum brasilense

Bible¹,

et al. 2008

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“…Mutants with mutations in cheB have the opposite phenotype, an increased frequency of switching (190). It is hard to imagine that CheB binds to the switch but not so far-fetched to imagine that CheC does, since it is homologous to most of the FliM and FliY proteins (two of the three proteins comprising the switch).…”

Section: Methylation-independent Adaptationmentioning

confidence: 99%

Diversity in Chemotaxis Mechanisms among the Bacteria and Archaea

Szurmant

Ordal

2004

Microbiol Mol Biol Rev

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413

439

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SUMMARY The study of chemotaxis describes the cellular processes that control the movement of organisms toward favorable environments. In bacteria and archaea, motility is controlled by a two-component system involving a histidine kinase that senses the environment and a response regulator, a very common type of signal transduction in prokaryotes. Most insights into the processes involved have come from studies of Escherichia coli over the last three decades. However, in the last 10 years, with the sequencing of many prokaryotic genomes, it has become clear that E. coli represents a streamlined example of bacterial chemotaxis. While general features of excitation remain conserved among bacteria and archaea, specific features, such as adaptational processes and hydrolysis of the intracellular signal CheY-P, are quite diverse. The Bacillus subtilis chemotaxis system is considerably more complex and appears to be similar to the one that existed when the bacteria and archaea separated during evolution, so that understanding this mechanism should provide insight into the variety of mechanisms used today by the broad sweep of chemotactic bacteria and archaea. However, processes even beyond those used in E. coli and B. subtilis have been discovered in other organisms. This review emphasizes those used by B. subtilis and these other organisms but also gives an account of the mechanism in E. coli.

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“…B. burgdorferi CheX shares approximately 25% amino acid sequence identity with Bacillus subtilis CheC, as well as with T. maritima CheC and CheX (31). In B. subtilis, a cheC mutant has decreased flagellar switching frequency (i.e., longer CCW and CW rotations), but the flagellar rotational bias (CCW versus CW) is unaltered (52). In addition, CheC possesses an enzymatic activity that weakly dephosphorylates CheY-P and increases significantly in the presence of CheD (62).…”

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confidence: 99%

CheX Is a Phosphorylated CheY Phosphatase Essential forBorrelia burgdorferiChemotaxis

Motaleb¹,

Miller

Li³

et al. 2005

J Bacteriol

112

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Motility and chemotaxis are believed to be important in the pathogenesis of Lyme disease caused by the spirochete Borrelia burgdorferi. Controlling the phosphorylation state of CheY, a response regulator protein, is essential for regulating bacterial chemotaxis and motility. Rapid dephosphorylation of phosphorylated CheY (CheY-P) is crucial for cells to respond to environmental changes. CheY-P dephosphorylation is accomplished by one or more phosphatases in different species, including CheZ, CheC, CheX, FliY, and/or FliY/N. Only a cheX phosphatase homolog has been identified in the B. burgdorferi genome. However, a role for cheX in chemotaxis has not been established in any bacterial species. Inactivating B. burgdorferi cheX by inserting a flgB-kan cassette resulted in cells (cheX mutant cells) with a distinct motility phenotype. While wild-type cells ran, paused (stopped or flexed), and reversed, the cheX mutant cells continuously flexed and were not able to run or reverse. Furthermore, swarm plate and capillary tube chemotaxis assays demonstrated that cheX mutant cells were deficient in chemotaxis. Wild-type chemotaxis and motility were restored when cheX mutant cells were complemented with a shuttle vector expressing CheX. Furthermore, CheX dephosphorylated CheY3-P in vitro and eluted as a homodimer in gel filtration chromatography. These findings demonstrated that B. burgdorferi CheX is a CheY-P phosphatase that is essential for chemotaxis and motility, which is consistent with CheX being the only CheY-P phosphatase in the B. burgdorferi chemotaxis signal transduction pathway.Bacteria move toward or away from environments that are favorable or unfavorable, respectively, to enhance their survival (reviewed in references 5, 63, and 65). When this movement is in response to chemicals, the process is termed chemotaxis. Flagella or periplasmic flagella, depending upon their location in a cell, are responsible for locomotion in many species of bacteria. Regulation of flagellar rotation and chemotaxis has been studied most extensively in Escherichia coli and Salmonella enterica serovar Typhimurium, and phosphorylation of the response regulator CheY plays an important role in regulating the swimming pattern of cells (reviewed in references 5, 8, 12, 60, 63, and 65). The concentration of phosphorylated CheY (CheY-P) determines whether a cell runs or tumbles. In the absence of attractants, the concentration of CheY-P is relatively high, and CheY-P diffuses to and binds the flagellar switch protein FliM, switching flagellar rotation from a default counterclockwise (CCW) state to a clockwise (CW) rotation. CW rotation of one or more flagella disrupts flagellar bundles, causing cells to tumble and reorient direction during the next run (37, 64). Although CheY-P autodephosphorylates, E. coli CheZ is required for efficient CheY-P dephosphorylation, allowing rapid responses to the environment (53). Thus, functionally reducing CheY-P in null mutants of cheA (encoding the protein that transfers phosphate to CheY) or cheY resu...

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Effect of loss of CheC and other adaptational proteins on chemotactic behaviour in Bacillus subtilis

Cited by 16 publications

References 60 publications

Function of a Chemotaxis-Like Signal Transduction Pathway in Modulating Motility, Cell Clumping, and Cell Length in the Alphaproteobacterium Azospirillum brasilense

Function of a Chemotaxis-Like Signal Transduction Pathway in Modulating Motility, Cell Clumping, and Cell Length in the Alphaproteobacterium Azospirillum brasilense

Diversity in Chemotaxis Mechanisms among the Bacteria and Archaea

CheX Is a Phosphorylated CheY Phosphatase Essential forBorrelia burgdorferiChemotaxis

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