Sensory rhodopsin‐controlled release of the switch factor fumarate in <i>Halobacterium salinarium</i>

Montrone, Marco; Marwan, Wolfgang; Grünberg, H. H. von; Musseleck, S; Starostzik, Christine; Oesterhelt, Dieter

doi:10.1111/j.1365-2958.1993.tb00978.x

Cited by 29 publications

(17 citation statements)

References 29 publications

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“…For the archaeon Halobacterium salinarium, we have identified fumarate as a factor required for switching the direction of rotation of the flagellar motor (24) and found that its cytoplasmic concentration is controlled by the photoreceptors (23,26). In eubacteria, fumarate also has switch factor activity, as demonstrated in an in vitro system.…”

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confidence: 88%

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Phosphorylation-independent bacterial chemoresponses correlate with changes in the cytoplasmic level of fumarate

1996

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Bacterial chemotaxis is based on modulation of the probability to switch the direction of flagellar rotation. Responses to many stimuli are transduced by a two-component system via reversible phosphorylation of CheY, a small cytoplasmic protein that directly interacts with the switch complex at the flagellar motor. We found that the chemorepellents indole and benzoate induce motor switching in Escherichia coli cells with a disabled phosphorylation cascade. This phosphorylation-independent chemoresponse is explained by reversible inhibition of fumarase by indole or benzoate which leads to an increased level of cellular fumarate, a compound involved in motor switching for bacteria and archaea. Genetic deletion of fumarase increased the intracellular concentration of fumarate and enhanced the switching frequency of the flagellar motors irrespective of the presence or absence of the phosphorylation cascade. These correlations provide evidence for fumaratedependent metabolic signal transduction in bacterial chemosensing.Motile procaryotes actively search for optimal living conditions. This phenomenon, called taxis, is based on the ability to sense environmental stimuli like chemicals, oxygen, and light and to respond by modulating the probability of switching the rotational sense of the motility organelle, the flagellar motor. The interplay of excitation and adaptation allows the cell to detect time-dependent changes in the strengths of different stimulus types; these changes are integrated to give a graded motor response (for reviews, see references 4, 12, and 22). Components of the bacterial sensory machinery have been identified and characterized by genetic, biochemical, and cell physiological methods. Bacterial chemotaxis provides a fascinating example of how computational information processing is performed by a network of proteins (8).

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confidence: 88%

“…The ether phase was quantitatively removed and evaporated under vacuum. The residual was redissolved in 0.2 ml of 0.1 M 3-amino-1-propanol buffer, pH 9.9, and assayed for fumarate as described by Montrone et al (26). The procedure was calibrated by adding fumarate as an internal standard to the boiling water used for lysing the cells.…”

Section: Methodsmentioning

confidence: 99%

Phosphorylation-independent bacterial chemoresponses correlate with changes in the cytoplasmic level of fumarate

1996

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“…The function of CheD and the CheC proteins, which build one of the three adaptation systems in B.subtilis [48], is unclear in Hbt.salinarum . The mechanism of action of the switch factor fumarate, which was discovered in Hbt.salinarum 20 years ago [49,50], is also unresolved.…”

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confidence: 99%

The protein interaction network of a taxis signal transduction system in a Halophilic Archaeon

et al. 2012

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BackgroundThe taxis signaling system of the extreme halophilic archaeon Halobacterium (Hbt.) salinarum differs in several aspects from its model bacterial counterparts Escherichia coli and Bacillus subtilis. We studied the protein interactions in the Hbt. salinarum taxis signaling system to gain an understanding of its structure, to gain knowledge about its known components and to search for new members.ResultsThe interaction analysis revealed that the core signaling proteins are involved in different protein complexes and our data provide evidence for dynamic interchanges between them. Fifteen of the eighteen taxis receptors (halobacterial transducers, Htrs) can be assigned to four different groups depending on their interactions with the core signaling proteins. Only one of these groups, which contains six of the eight Htrs with known signals, shows the composition expected for signaling complexes (receptor, kinase CheA, adaptor CheW, response regulator CheY). From the two Hbt. salinarum CheW proteins, only CheW1 is engaged in signaling complexes with Htrs and CheA, whereas CheW2 interacts with Htrs but not with CheA. CheY connects the core signaling structure to a subnetwork consisting of the two CheF proteins (which build a link to the flagellar apparatus), CheD (the hub of the subnetwork), two CheC complexes and the receptor methylesterase CheB.ConclusionsBased on our findings, we propose two hypotheses. First, Hbt. salinarum might have the capability to dynamically adjust the impact of certain Htrs or Htr clusters depending on its current needs or environmental conditions. Secondly, we propose a hypothetical feedback loop from the response regulator to Htr methylation made from the CheC proteins, CheD and CheB, which might contribute to adaptation analogous to the CheC/CheD system of B. subtilis.

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“…Besides CheY-P, fumarate is a further factor involved in flagellar motor switching, both in archaea ( H. salinarum , [46,47]) and bacteria ( E. coli and S. typhimurium , [48]). In E. coli , fumarate reductase (FRD) was identified as the target of fumarate at the motor, where it was shown to interact with the flagellar motor switch protein FliG [49].…”

Section: Introductionmentioning

confidence: 99%

Identification of Archaea-specific chemotaxis proteins which interact with the flagellar apparatus

et al. 2009

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BackgroundArchaea share with bacteria the ability to bias their movement towards more favorable locations, a process known as taxis. Two molecular systems drive this process: the motility apparatus and the chemotaxis signal transduction system. The first consists of the flagellum, the flagellar motor, and its switch, which allows cells to reverse the rotation of flagella. The second targets the flagellar motor switch in order to modulate the switching frequency in response to external stimuli. While the signal transduction system is conserved throughout archaea and bacteria, the archaeal flagellar apparatus is different from the bacterial one. The proteins constituting the flagellar motor and its switch in archaea have not yet been identified, and the connection between the bacterial-like chemotaxis signal transduction system and the archaeal motility apparatus is unknown.ResultsUsing protein-protein interaction analysis, we have identified three proteins in Halobacterium salinarum that interact with the chemotaxis (Che) proteins CheY, CheD, and CheC2, as well as the flagella accessory (Fla) proteins FlaCE and FlaD. Two of the proteins belong to the protein family DUF439, the third is a HEAT_PBS family protein. In-frame deletion strains for all three proteins were generated and analyzed as follows: a) photophobic responses were measured by a computer-based cell tracking system b) flagellar rotational bias was determined by dark-field microscopy, and c) chemotactic behavior was analyzed by a swarm plate assay. Strains deleted for the HEAT_PBS protein or one of the DUF439 proteins proved unable to switch the direction of flagellar rotation. In these mutants, flagella rotate only clockwise, resulting in exclusively forward swimming cells that are unable to respond to tactic signals. Deletion of the second DUF439 protein had only minimal effects. HEAT_PBS proteins could be identified in the chemotaxis gene regions of all motile haloarchaea sequenced so far, but not in those of other archaeal species. Genes coding for DUF439 proteins, however, were found to be integral parts of chemotaxis gene regions across the archaeal domain, and they were not detected in other genomic context.ConclusionAltogether, these results demonstrate that, in the archaeal domain, previously unrecognized archaea-specific Che proteins are essential for relaying taxis signaling to the flagellar apparatus.

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Sensory rhodopsin‐controlled release of the switch factor fumarate in Halobacterium salinarium

Cited by 29 publications

References 29 publications

Phosphorylation-independent bacterial chemoresponses correlate with changes in the cytoplasmic level of fumarate

Phosphorylation-independent bacterial chemoresponses correlate with changes in the cytoplasmic level of fumarate

The protein interaction network of a taxis signal transduction system in a Halophilic Archaeon

Identification of Archaea-specific chemotaxis proteins which interact with the flagellar apparatus

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