Bacillus subtilis CheC and FliY Are Members of a Novel Class of CheY-P-hydrolyzing Proteins in the Chemotactic Signal Transduction Cascade

Szurmant, Hendrik; Muff, Travis J.; Ordal, George

doi:10.1074/jbc.m311497200

Cited by 88 publications

(117 citation statements)

References 35 publications

(34 reference statements)

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“…E. coli, Bacillus subtilis, and Vibrio cholerae, can manage with only one (45,46)? Sinorhizobium meliloti and R. sphaeroides lack the CheZ, CheC, CheX, and FliY signal terminating CheY phosphatases that have been described in other bacteria (47)(48)(49). Like R. sphaeroides, S. meliloti also requires two CheYs for normal chemotaxis; S. meliloti CheY2-P can bind to the FliM component of the flagellar motor and bring about direction changing, whereas CheY1 cannot bind to the motor and acts as a signal terminating phosphate sink (50).…”

Section: Discussionmentioning

confidence: 99%

The CheYs of Rhodobacter sphaeroides

Porter

Wadhams

Martin

et al. 2006

Journal of Biological Chemistry

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The Escherichia coli two-component chemosensory pathway has been extensively studied, and its response regulator, CheY, has become a paradigm for response regulators. However, unlike E. coli, most chemotactic nonenteric bacteria have multiple CheY homologues. The roles and cellular localization of the CheYs in Rhodobacter sphaeroides were determined. Only two CheYs were required for chemotaxis, CheY 6 and either CheY 3 or CheY 4 . These CheYs were partially localized to either of the two chemotaxis signaling clusters, with the remaining protein delocalized. Interestingly, mutation of the CheY 6 phosphorylatable aspartate to asparagine produced a stopped motor, caused by phosphorylation on alternative site Ser-83 by CheA. Extensive mutagenesis of E. coli CheY has identified a number of activating mutations, which have been extrapolated to other response regulators (D13K, Y106W, and I95V). Analogous mutations in R. sphaeroides CheYs did not cause activation. These results suggest that although the R. sphaeroides and E. coli CheYs are similar in that they require phosphorylation for activation, they may differ in both the nature of the phosphorylation-induced conformational change and their subsequent interactions with the flagellar motor. Caution should therefore be used when projecting from E. coli CheY onto novel response regulators.

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Section: Discussionmentioning

confidence: 99%

The CheYs of Rhodobacter sphaeroides

Porter

Wadhams

Martin

et al. 2006

Journal of Biological Chemistry

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“…We used a smooth-swimming strain of the bacterium B. subtilis, strain OI4139 (25), which is a mutant that almost never tumbles. The cells have an ellipsoidal body with average size of 1 × 3 μm.…”

Section: Methodsmentioning

confidence: 99%

Bacterial rheotaxis

Marcos

Powers

et al. 2012

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

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The motility of organisms is often directed in response to environmental stimuli. Rheotaxis is the directed movement resulting from fluid velocity gradients, long studied in fish, aquatic invertebrates, and spermatozoa. Using carefully controlled microfluidic flows, we show that rheotaxis also occurs in bacteria. Excellent quantitative agreement between experiments with Bacillus subtilis and a mathematical model reveals that bacterial rheotaxis is a purely physical phenomenon, in contrast to fish rheotaxis but in the same way as sperm rheotaxis. This previously unrecognized bacterial taxis results from a subtle interplay between velocity gradients and the helical shape of flagella, which together generate a torque that alters a bacterium's swimming direction. Because this torque is independent of the presence of a nearby surface, bacterial rheotaxis is not limited to the immediate neighborhood of liquid-solid interfaces, but also takes place in the bulk fluid. We predict that rheotaxis occurs in a wide range of bacterial habitats, from the natural environment to the human body, and can interfere with chemotaxis, suggesting that the fitness benefit conferred by bacterial motility may be sharply reduced in some hydrodynamic conditions. low Reynolds number | directional motion | chirality T he effectiveness and benefit of motility are largely determined by the dependence of movement behavior on environmental stimuli. For example, chemical stimuli may affect the spreading of tumor cells (1) and allow bacteria to increase uptake by swimming toward larger nutrient concentrations (2, 3), whereas hydrodynamic stimuli can stifle phytoplankton migration (4), allow protists to evade predators (5), and change sperm-egg encounter rates for external fertilizers (6). Microorganisms exhibit a broad range of directed movement responses, called "taxes". Whereas some of these responses, such as chemotaxis (7) and thermotaxis (8), are active and require the ability to sense and respond to the stimulus, others, such as magnetotaxis (9) and gyrotaxis (4), are passive and do not imply sensing, instead resulting purely from external forces.Chemotaxis is the best studied among these directional motions: Bacteria measure chemical concentrations and migrate along gradients (Fig. 1A). For instance, chemotaxis guides Escherichia coli to epithelial cells in the human gastrointestinal tract, favoring infection (10); Rhizobium bacteria to legume root hairs in soil, favoring nitrogen fixation (2); and marine bacteria to organic matter, favoring remineralization (3). Equally as pervasive as chemical gradients in microbial habitats are gradients in ambient fluid velocity or "shear" (Fig. 1B). Although nearly every fluid environment experiences velocity gradientsfrom laminar shear in bodily conduits and soil to turbulent shear in streams and oceans-the effect of velocity gradients on bacterial motility has received negligible attention compared with chemical gradients, partly due to the difficulty of studying motility under controlled flow conditi...

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“…By biasing the duration and frequency of run and tumble swimming events, the bacterium is able to migrate up gradients of attractant molecules. In addition to this core signal transduction module, the B. subtilis pathway also possesses two CheY-P phosphatases and a number of regulatory proteins involved in sensory adaptation (6,7). One of the remarkable features of the chemotaxis system is its ability to adapt the bacteria to their surrounding environment so that relative changes in the chemical concentrations can be sensitively detected.…”

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confidence: 99%

A PAS Domain Binds Asparagine in the Chemotaxis Receptor McpB in Bacillus subtilis

Glekas

Foster

Cates

et al. 2010

Journal of Biological Chemistry

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During chemotaxis toward asparagine by Bacillus subtilis, the ligand is thought to bind to the chemoreceptor McpB on the exterior of the cell and induce a conformational change. This change affects the degree of phosphorylation of the CheA kinase bound to the cytoplasmic region of the receptor. Until recently, the sensing domains of the B. subtilis receptors were thought to be structurally similar to the well studied Escherichia coli fourhelical bundle. However, sequence analysis has shown the sensing domains of receptors from these two organisms to be vastly different. Homology modeling of the sensing domain of the B. subtilis asparagine receptor McpB revealed two tandem PAS domains. McpB mutants having alanine substitutions in key arginine and tyrosine residues of the upper PAS domain but not in any residues of the lower PAS domain exhibited a chemotactic defect in both swarm plates and capillary assays. Thus, binding does not appear to occur across any dimeric surface but within a monomer. A modified capillary assay designed to determine the concentration of attractant where chemotaxis is most sensitive showed that when Arg-111, Tyr-121, or Tyr-133 is mutated to an alanine, much more asparagine is required to obtain an active chemoreceptor. Isothermal titration calorimetry experiments on the purified sensing domain showed a K D to asparagine of 14 M, with the three mutations leading to less efficient binding. Taken together, these results reveal not only a novel chemoreceptor sensing domain architecture but also, possibly, a different mechanism for chemoreceptor activation.Many species of bacteria are able to sense their proximal chemical environment and move toward more favorable locations through a process known as chemotaxis. At the heart of all known bacterial chemotaxis pathways is a two-component signal transduction system involving the CheA histidine kinase and the CheY response regulator. In the Gram-positive bacterium Bacillus subtilis, the CheA kinase forms a stable complex with the chemotaxis receptors, also known as methyl-accepting chemotaxis proteins (MCPs), and the CheW and CheV adaptor proteins (1). When the receptors sense attractant molecules, they enhance the rate of CheA autophosphorylation, which in turn causes CheY-P concentrations to increase (2-4). In B. subtilis, the binding of CheY-P to the cytoplasmic face of the flagellum increases the likelihood of smooth runs (5). By biasing the duration and frequency of run and tumble swimming events, the bacterium is able to migrate up gradients of attractant molecules. In addition to this core signal transduction module, the B. subtilis pathway also possesses two CheY-P phosphatases and a number of regulatory proteins involved in sensory adaptation (6, 7). One of the remarkable features of the chemotaxis system is its ability to adapt the bacteria to their surrounding environment so that relative changes in the chemical concentrations can be sensitively detected.The chemotaxis receptors have previously been shown to be long, ␣-helical homodime...

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Bacillus subtilis CheC and FliY Are Members of a Novel Class of CheY-P-hydrolyzing Proteins in the Chemotactic Signal Transduction Cascade

Cited by 88 publications

References 35 publications

The CheYs of Rhodobacter sphaeroides

The CheYs of Rhodobacter sphaeroides

Bacterial rheotaxis

A PAS Domain Binds Asparagine in the Chemotaxis Receptor McpB in Bacillus subtilis

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