Repellents for Escherichia coli operate neither by changing membrane fluidity nor by being sensed by periplasmic receptors during chemotaxis

Eisenbach, Michael; Constantinou, Constantina; Aloni, Hamutal; Shinitzky, Meir

doi:10.1128/jb.172.9.5218-5224.1990

Cited by 24 publications

(17 citation statements)

References 59 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The data do not exclude the possibility that any one of the MCPs may be sufficient for the formation of patterns, as in the case of negative chemotactic response to aliphatic alcohols, glycerol, and ethylene glycol (12,28,29). Also, the receptor may be one which has not yet been discovered, or the pathway may be a proton motive force (PMF)-mediated one (13,40).…”

Section: Discussionmentioning

confidence: 95%

Tar-dependent and -independent pattern formation by Salmonella typhimurium

Blat

Eisenbach

1995

J Bacteriol

Self Cite

View full text Add to dashboard Cite

When Salmonella typhimurium cells were allowed to swarm on either a minimal or complex semisolid medium, patterns of cell aggregates were formed (depending on the thickness of the medium). No patterns were observed with nonchemotactic mutants. The patterns in a minimal medium were not formed by a mutant in the aspartate receptor for chemotaxis In bacteria and other unicellular organisms, each cell constitutes an independent entity. Each of the cells can sense and respond to changes in the composition of the environment. The signals received from the environment are diverse and include signals that indicate the availability of carbon, nitrogen, and phosphate sources, changes in the temperature, and an optimal concentration of oxygen (22,37). The response to these signals is usually modulation of gene expression (for reviews, see references 6, 31, and 38). The response to chemotactic signals from the environment does not involve changes in gene expression. Protein synthesis is too slow to enable the immediate response required for chemotaxis (the response time is 50 to 120 ms [19]). Instead, the chemotaxis process is mediated by chemical modifications of the chemotaxis proteins (see references 6,11,15,21,24, and 39 for recent reviews).A variety of compounds serve as attractants or repellents for chemotaxis of Escherichia coli and Salmonella typhimurium. Sugars, oxygen, and some amino acids are attractants, whereas other amino acids, some hydrophobic compounds, and deleterious ions are repellents. The sensing of all of these signals is carried out by more then 10 different receptors, each of which has its own specific set of ligands (3,22,25). The best-characterized receptors with the largest variety of known ligands are the methyl-accepting chemotaxis proteins (MCPs). They are Tsr, Tar, Trg, and (in E. coli) Tap or (in S. typhimurium) Tcp, the first two being the most abundant ones in the cell.The complex sensing machinery of chemotaxis may not be restricted to signals received from the environment. In principle, the chemotaxis receptors can also be exploited for communication between bacterial cells. A single compelling example for such communication has already been reported. Myxobacteria, which are gliding bacteria, can form fruiting bodies composed of 10 5 cells when nutrient supplies are deficient. The formation of the fruiting bodies is dependent on chemotaxis toward the growing fruiting bodies; the signal has not been identified (20).Recently, Budrene and Berg observed patterns of cell aggregates formed by E. coli, a swimming bacterium, on semisolid minimal medium and suggested that cell-to-cell communication is involved in this pattern formation (8). A similar observation has been made in S. typhimurium (7, 9). The formation of these patterns seem to be mediated by a signal released from the bacteria and sensed by the chemotaxis aspartate receptor Tar (MCP II) (8, 9). Here we report that S. typhimurium forms patterns of cell aggregates not only on semisolid minimal media but also on semisolid complex media...

show abstract

Section: Discussionmentioning

confidence: 95%

Tar-dependent and -independent pattern formation by Salmonella typhimurium

Blat

Eisenbach

1995

J Bacteriol

Self Cite

View full text Add to dashboard Cite

show abstract

“…From this, one would expect that changes in membrane properties would affect CheA activity. For example, CheA is activated in vivo by alcohols that tend to make the membrane more fluid (43), as well as by increases in osmolarity that cause plasmolysis with attendant membrane invaginations (44).…”

Section: Discussionmentioning

confidence: 99%

Self-assembly of receptor/signaling complexes in bacterial chemotaxis

Wolanin¹,

Baker

Francis³

et al. 2006

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

View full text Add to dashboard Cite

Escherichia coli chemotaxis is mediated by membrane receptor͞ histidine kinase signaling complexes. Fusing the cytoplasmic domain of the aspartate receptor, Tar, to a leucine zipper dimerization domain produces a hybrid, lzTar C, that forms soluble complexes with CheA and CheW. The three-dimensional reconstruction of these complexes was different from that anticipated based solely on structures of the isolated components. We found that analogous complexes self-assembled with a monomeric cytoplasmic domain fragment of the serine receptor without the leucine zipper dimerization domain. These complexes have essentially the same size, composition, and architecture as those formed from lzTar C. Thus, the organization of these receptor͞signaling complexes is determined by conserved interactions between the constituent chemotaxis proteins and may represent the active form in vivo. To understand this structure in its cellular context, we propose a model involving parallel membrane segments in receptor-mediated CheA activation in vivo.CheA ͉ histidine kinase ͉ serine receptor ͉ signal transduction

show abstract

“…No binding of any chemorepellent to any chemotaxis receptor has been demonstrated, although, in vivo, the responses to most chemorepellents are mediated by one or more MCPs. It was proposed that the MCPs are low-affinity receptors for chemorepellents (Eisenbach et al, 1990a).…”

Section: Signal Transduction In Response To Negative Stimulationmentioning

confidence: 99%

Bacterial Chemotaxis

Eisenbach

2011

Encyclopedia of Life Sciences

View full text Add to dashboard Cite

Bacteria can move by a variety of means, the most common one by rotating their flagella. This movement is often directed towards favourable chemicals (chemoattractants) or away from unfavourable chemicals (chemorepellents), a process termed chemotaxis. This modulation of swimming direction is the outcome of controlled changes in the direction of flagellar rotation. Therefore, mechanistically, the essence of bacterial chemotaxis is to control the direction of flagellar rotation. This control is done by a sophisticated signal transduction system, involving a small protein, CheY, which shuttles back and forth between the receptor complexes clustered at the pole of the cell and the flagellar motor complexes around the cell. These interactions are modulated by phosphorylation and acetylation. The excitatory signalling process involves amplification. The adaptation signalling involves methylation of the receptors. Even though bacterial chemotaxis is considered the best understood signalling system at the molecular level, many major questions are still waiting to be resolved. Key Concepts: In bacteria, chemotaxis is the motile response to stimuli and it serves as a means of cell–environment and cell‐to‐cell communication. Bacteria sense stimulant gradients (chemoattractants and chemorepellents) temporally rather than spatially. The chemotaxis‐specific receptors are clustered at the bacterial poles. This clustering is essential for signalling and amplification. Bacteria swim by rotating their flagella. The direction of rotation determines the swimming mode. Therefore, the essence of bacterial chemotaxis is to control the direction of flagellar rotation. The direction of flagellar rotation is modulated by the signalling molecule, CheY, according to changes in receptor occupancy. CheY function is modulated by phosphorylation at both the excitatory and adaptation signalling phases. The latter also involves receptor carboxy methylation. Phosphorylated CheY binds to the switch at the base of the flagellar motor and, thereby, changes the direction of rotation.

show abstract

Repellents for Escherichia coli operate neither by changing membrane fluidity nor by being sensed by periplasmic receptors during chemotaxis

Cited by 24 publications

References 59 publications

Tar-dependent and -independent pattern formation by Salmonella typhimurium

Tar-dependent and -independent pattern formation by Salmonella typhimurium

Self-assembly of receptor/signaling complexes in bacterial chemotaxis

Bacterial Chemotaxis

Contact Info

Product

Resources

About