Phosphotransfer between CheA, CheY1, and CheY2 in the Chemotaxis Signal Transduction Chain of <i>Rhizobium meliloti</i>

Sourjik, Victor; Schmitt, Rüdiger

doi:10.1021/bi972330a

Cited by 150 publications

(155 citation statements)

References 38 publications

(50 reference statements)

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“…A second mechanism of CheY-P removal has been demonstrated in Sinorhizobium meliloti and other ␣-proteobacteria (26,27). These organisms encode at least two alternative CheY proteins.…”

Section: Resultsmentioning

confidence: 98%

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

Szurmant¹,

Muff²,

Ordal

2004

Journal of Biological Chemistry

115

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Rapid restoration of prestimulus levels of the chemotactic response regulator, CheY-P, is important for preparing bacteria and archaea to respond sensitively to new stimuli. In an extension of previous work (Szurmant, H., Bunn, M. W., Cannistraro, V. J., and Ordal, G. W. (2003) J. Biol. Chem. 278, 48611-48616), we describe a new family of CheY-P phosphatases, the CYX family, that is widespread among the bacteria and archaea. These proteins provide another pathway, in addition to the ones involving CheZ of the ␥-and ␤-proteobacteria (e.g. Escherichia coli) or the alternative CheY that serves as a "phosphate sink" among the ␣-proteobacteria (e.g. Sinorhizobium meliloti), for dephosphorylating CheY-P. In particular, we identify CheC, known previously to be involved in adaptation to stimuli in Bacillus subtilis, as a CheY-P phosphatase. Using an in vitro assay used previously to demonstrate that the switch protein FliY is a CheY-P phosphatase, we have shown that increasing amounts of CheC accelerate the hydrolysis of CheY-P. In vivo, a double mutant lacking cheC and the region of fliY that encodes the CheY-P binding domain is almost completely smooth swimming, implying that these cells contain very high levels of CheY-P. CheC appears to be primarily involved in restoring normal CheY-P levels following the addition of attractant, whereas FliY seems to act on CheY-P constitutively. The activity of CheC is relatively low compared to that of FliY, but we have shown that the chemotaxis protein CheD enhances the activity of CheC 5-fold. We suggest a model for how FliY, CheC, and CheD work together to regulate CheY-P levels in the bacterium.

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“…A second mechanism of CheY-P removal has been demonstrated in Sinorhizobium meliloti and other ␣-proteobacteria (26,27). These organisms encode at least two alternative CheY proteins.…”

Section: Resultsmentioning

confidence: 98%

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

Szurmant¹,

Muff²,

Ordal

2004

Journal of Biological Chemistry

115

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“…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). Could R. sphaeroides be using a similar system?…”

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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“…This is the hallmark of a different mechanism for rapidly dephosphorylating CheY2-P (the orthologue of the E. coli CheY-P). The phosphate from surplus CheY2-P (but not from CheY1-P) is shuttled back to CheA, which in turn phosphorylates free CheY1 (Sourjik & Schmitt, 1998). Retro-phosphorylation via CheA thus accelerates the deactivation of CheY2-P (Fig.…”

Section: Signalling Pathwaysmentioning

confidence: 99%

“…Since intracellular concentrations of CheY1 are roughly in 10-fold excess over CheA, the former acts like a sponge (or ' sink') by absorbing the phosphoryl groups from CheA-P. However, as phosphorylation of CheY1 by CheA-P requires in the order of 50-100 ms, spontaneous auto-dephosphorylation of CheY1-P (τ\ # "10 s ; Sourjik & Schmitt, 1998) may be too slow to provide sufficient free CheY1. It is not clear yet whether S. meliloti has a device for accelerating the dephosphorylation of CheY1-P, in analogy to the enterobacterial CheZ.…”

Section: Signalling Pathwaysmentioning

confidence: 99%

“…Retro-phosphorylation in the sensory transduction chain as a mechanism for efficient dephosphorylation of the response regulator CheY2-P, and hence for rapid adaptation to new stimuli, was initially considered a peculiarity of S. meliloti (Sourjik & Schmitt, 1998). However, an inspection of well-analysed α-proteobacteria and of some recently published genome sequences of other non-enterics revealed the presence of CheY1 and CheY2 paralogues concurrent with the absence of CheZ in many of these bacterial species.…”

Section: Signalling Pathwaysmentioning

confidence: 99%

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Phosphotransfer between CheA, CheY1, and CheY2 in the Chemotaxis Signal Transduction Chain of Rhizobium meliloti

Cited by 150 publications

References 38 publications

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

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

The CheYs of Rhodobacter sphaeroides

Sinorhizobial chemotaxis: a departure from the enterobacterial paradigm a aTo Professor Wolfram Heumann on his 87th birthday.

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