Signaling Interactions between the Aerotaxis Transducer Aer and Heterologous Chemoreceptors in
            <i>Escherichia coli</i>

Gosink, Khoosheh K.; Burón-Barral, Maria del Carmen; Parkinson, John S.

doi:10.1128/jb.188.10.3487-3493.2006

Cited by 53 publications

(62 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A custom-made trigger box controlled the shutter via electronic circuitry (25,31) to set the delay of the light pulse relative to the initiation of image acquisition and its duration. Alternatively, it was used to trigger discharge of a flash lamp (22) for photorelease of L-serine, L-aspartate, or molecular oxygen from photolabile derivatives.…”

mentioning

confidence: 99%

“…Photolabile N-1-(2-nitrophenyl)ethoxycarbonyl derivatives of L-serine and Laspartate have been described previously (31,32 The Tsr and Aer plasmids used in this study were derivatives of pCJ30 (7), an IPTG-inducible expression vector derived from pBR322 that confers ampicillin resistance: pPA56 (Tsr[290-470]) (4); pJC3 (wild-type Tsr) (5); pSB20 (wild-type Aer) (7); and pSB20 derivatives encoding mutant Aer proteins (7,22). The wild-type Tar expression plasmid pLC113 (5) and the wild-type Aer expression plasmid pKG117 (16) were derived from a salicylate-inducible expression vector that confers chloramphenicol resistance (pLC112) (5).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Differential Activation of Escherichia coli Chemoreceptors by Blue-Light Stimuli

et al. 2006

Self Cite

View full text Add to dashboard Cite

Enteric bacteria tumble, swim slowly, and are then paralyzed upon exposure to 390-to 530-nm light. Here, we analyze this complex response in Escherichia coli using standard fluorescence microscope optics for excitation at 440 ؎ 5 nm. The slow swimming and paralysis occurred only in dye-containing growth media or buffers. Excitation elicited complete paralysis within a second in 1 M proflavine dye, implying specific motor damage, but prolonged tumbling in buffer alone. The tumbling half-response times were subsecond for onset but more than a minute for recovery. The response required the chemotaxis signal protein CheY and receptordependent activation of its kinase CheA. The study of deletion mutants revealed a specific requirement for either the aerotaxis receptor Aer or the chemoreceptor Tar but not the Tar homolog Tsr. The action spectrum of the wild-type response was consistent with a flavin, but the chromophores remain to be identified. The motile response processed via Aer was sustained, with recovery to either step-up or -down taking more than a minute. The response processed via Tar was transient, recovering on second time scales comparable to chemotactic responses. The response duration and amplitude were dependent on relative expression of Aer, Tar, and Tsr. The main response features were reproduced when each receptor was expressed singly from a plasmid in a receptorless host strain. However, time-resolved motion analysis revealed subtle kinetic differences that reflect the role of receptor cluster interactions in kinase activation-deactivation dynamics.

show abstract

mentioning

confidence: 99%

mentioning

confidence: 99%

Differential Activation of Escherichia coli Chemoreceptors by Blue-Light Stimuli

et al. 2006

Self Cite

View full text Add to dashboard Cite

show abstract

“…We would not have detected such fragments in our degradation assays because the Aer antibodies we used in Western analyses were directed against Aer residues 1 to 263. Most epitopes lie in the PAS domain, which is probably the site of initial proteolytic cleavage during degradation (12). At this point, we cannot be certain that dominance involves mutant Aer fragments because the presence of wild-type Aer subunits could conceivably modify or alleviate the maturation defects of some mutant Aer subunits.…”

Section: Discussionmentioning

confidence: 99%

“…Cells were harvested by centrifugation, washed once in phosphate-buffered saline (pH 7.4), and lysed by boiling for 10 min in sodium dodecyl sulfate (SDS) sample buffer (15), followed by freezing and thawing. Samples were analyzed by electrophoresis in 10% SDS-containing polyacrylamide gels and immunoblotting with a polyclonal rabbit antiserum directed against Aer residues 1 to 263 (12). Aer bands were visualized using Cy5-labeled goat anti-rabbit immunoglobulin G (heavy plus light chains; Amersham) and quantified with a Molecular Dynamics Typhoon 8600 imager.…”

Section: Methodsmentioning

confidence: 99%

Loss- and Gain-of-Function Mutations in the F1-HAMP Region of theEscherichia coliAerotaxis Transducer Aer

2006

Self Cite

View full text Add to dashboard Cite

The Escherichia coli Aer protein contains an N-terminal PAS domain that binds flavin adenine dinucleotide (FAD), senses aerotactic stimuli, and communicates with the output signaling domain. To explore the roles of the intervening F1 and HAMP segments in Aer signaling, we isolated plasmid-borne aerotaxis-defective mutations in a host strain lacking all chemoreceptors of the methyl-accepting chemotaxis protein (MCP) family. Under these conditions, Aer alone established the cell's run/tumble swimming pattern and modulated that behavior in response to oxygen gradients. We found two classes of Aer mutants: null and clockwise (CW) biased. Most mutant proteins exhibited the null phenotype: failure to elicit CW flagellar rotation, no aerosensing behavior in MCP-containing hosts, and no apparent FAD-binding ability. However, null mutants had low Aer expression levels caused by rapid degradation of apparently nonnative subunits. Their functional defects probably reflect the absence of a protein product. In contrast, CW-biased mutant proteins exhibited normal expression levels, wild-type FAD binding, and robust aerosensing behavior in MCP-containing hosts. The CW lesions evidently shift unstimulated Aer output to the CW signaling state but do not block the Aer input-output pathway. The distribution and properties of null and CW-biased mutations suggest that the Aer PAS domain may engage in two different interactions with HAMP and the HAMP-proximal signaling domain: one needed for Aer maturation and another for promoting CW output from the Aer signaling domain. Most aerotaxis-defective null mutations in these regions seemed to affect maturation only, indicating that these two interactions involve structurally distinct determinants.The Aer protein of Escherichia coli promotes movement toward optimal concentrations of oxygen and other electron acceptors (8,20). Aer homologs have been found in many other species of bacteria, where they probably mediate similar aerotactic behaviors. Aer communicates with the flagellar motors through a cytoplasmic signaling domain that modulates the activity of the histidine kinase CheA to control the phosphorylation state of the CheY response regulator. The Aer signaling domain is closely related to that of transmembrane chemoreceptors of the methyl-accepting chemotaxis protein (MCP) family, but Aer differs from orthodox MCPs in several important respects. First, the Aer signaling domain does not employ reversible methylation changes for sensory adaptation. Second, the Aer molecule, although membrane associated, does not have a periplasmic sensing domain but rather a cytoplasmic PAS domain that is thought to sense oxygen stimuli by monitoring cellular electron transport activity. PAS domains are widespread in proteins that sense cellular energy levels, redox potential, light, and other stimuli (24). The PAS structural motif comprises a binding pocket that can be adapted for a variety of small-molecule ligands, such as heme (in FixL). In the case of Aer, the PAS ligand is flavin adenine dinucle...

show abstract

“…E. coli generally have five different types of receptors (Tar, Tsr, Trg, Tap and Aer) that differ in their sensitivities to different attractants and repellents, and form mixed clusters of homodimers (Studdert & Parkinson, 2005) at the cell poles (Maddock & Shapiro, 1993) in proportion to their relative abundance in the cells (Studdert & Parkinson, 2004;Gosink et al, 2006). As reviewed recently (Hazelbauer et al, 2008), binding of an attractant chemical to the periplasmic sensing domain of a chemoreceptor molecule decreases the activity of a histidine kinase (CheA) coupled, via the CheW protein, to its cytoplasmic signalling domain.…”

Section: Introductionmentioning

confidence: 99%

Variable length tandem repeat polyglutamine sequences in the flexible tether region of the Tsr chemotaxis receptor of Escherichia coli

et al. 2008

View full text Add to dashboard Cite

Methyl-accepting chemotaxis proteins (MCPs) are receptors that play an important role in bacterial chemotaxis. Methylation of Tsr, the MCP that mediates chemotaxis towards serine in Escherichia coli, is thought to be facilitated by binding of the methyltransferase to a flexible tether region at the C-terminal end of Tsr. This study analysed natural length variants of the tether that occur in E. coli due to genetic instability in tandem repeat DNA sequences that code for glutaminyl (Q) residues, creating polyQ sequences of variable lengths in the tether region. The tsr gene of E. coli K-12 (strain MG1655) codes for 4Q at the beginning of its 35 aa tether region. The tether varies in length from 35 to 47 residues among pathogenic and non-pathogenic strains of Escherichia, Shigella spp., Salmonella, Yersinia and Photorhabdus. Among previous sequences, Escherichia and Shigella mostly have 4Q and 7Q variants, and one strain (E. coli HS) has 10Q. In E. coli isolated from 50 humans and 75 animals (dogs, cats, horses, birds, etc.), polyQ up to 13Q (44 aa tether) were identified (6 strains); relative frequencies were 7Q (~77 % of the total) .4Q (14 %) .13Q (5 %) .10Q (4 %). Phylogenetic analysis revealed that E. coli strains with 10Q or 13Q largely fell within two clusters. Serine chemotaxis was not significantly different among 7Q, 10Q and 13Q strains, and was comparable to chemotaxis in the frequently studied K-12 strain. These results are consistent with models indicating that polyQ sequences from 7Q to13Q are flexible, and that longer tethers, within this range, would not change the precision of adaptation mediated by methylation. Studies of this naturally variable polyQ region in E. coli may also have relevance to mechanisms that mediate polyQ instability in human genetic diseases. INTRODUCTIONThe receptors that mediate one form of chemotactic behaviour in bacteria have been an important focus of study since Adler and colleagues first described them in Escherichia coli (Adler, 1969;Springer et al., 1979). E. coli generally have five different types of receptors (Tar, Tsr, Trg, Tap and Aer) that differ in their sensitivities to different attractants and repellents, and form mixed clusters of homodimers (Studdert & Parkinson, 2005) at the cell poles (Maddock & Shapiro, 1993) in proportion to their relative abundance in the cells (Studdert & Parkinson, 2004;Gosink et al., 2006). As reviewed recently (Hazelbauer et al., 2008), binding of an attractant chemical to the periplasmic sensing domain of a chemoreceptor molecule decreases the activity of a histidine kinase (CheA) coupled, via the CheW protein, to its cytoplasmic signalling domain. Decreased CheA activity lowers the phosphorylation state of the flagellar motor regulator, CheY, thereby increasing the probability of counterclockwise flagellar rotation, which mediates forward swimming. The signalling properties of the chemoreceptors, except for Aer, are also regulated by methylation and demethylation of several specific glutamyl residues in their cytoplasmic domain...

show abstract

Signaling Interactions between the Aerotaxis Transducer Aer and Heterologous Chemoreceptors in Escherichia coli

Cited by 53 publications

References 27 publications

Differential Activation of Escherichia coli Chemoreceptors by Blue-Light Stimuli

Differential Activation of Escherichia coli Chemoreceptors by Blue-Light Stimuli

Loss- and Gain-of-Function Mutations in the F1-HAMP Region of theEscherichia coliAerotaxis Transducer Aer

Variable length tandem repeat polyglutamine sequences in the flexible tether region of the Tsr chemotaxis receptor of Escherichia coli

Contact Info

Product

Resources

About