Disease relevance of tsr

• We present here the nucleotide sequence of the tsr gene of E. coli; the amino acid sequence derived from it suggests that the Tsr transducer protein has a relatively simple transmembrane structure that may place limits on the mechanisms available for the transmission of sensory information into the cell [1].
• Synthesis of the tsr and tar products was directed in ultraviolet-irradiated bacteria by lambda transducing phages [2].
• We demonstrate here that the expression of the Escherichia coli chemoreceptor gene tsr, with 2.6 kilobases of its upstream sequence, is temporally controlled in Caulobacter crescentus [3].
• Streptomyces viridochromogenes was transformed by single stranded DNA integration vectors in order to replace the pat by the tsr gene and generate mutants unable to synthesize phosphinothricin-tripeptide (PTT) [4].
• We characterized mutants in two novel genes of Bacillus subtilis, cheC and cheD [5].

High impact information on tsr

• The tsr and tar genes, which are widely separated in the E. coli genome, encode functionally analogous transducer proteins that focus and integrate two distinct classes of chemosensory information [6].
• DNA hybridization studies demonstrated that the tsr gene possesses sequence homologies with the tar and tap genes, suggesting that they have all evolved from a common ancestor [6].
• The sensory transducers are the products of four genes: tsr, tar, tap and trg [1].
• A double mutant deficient in aer and tsr, which codes for the serine chemoreceptor, was negative for aerotaxis, redox taxis, and glycerol taxis, each of which requires the proton motive force and/or electron transport system for signaling [7].
• The tsr gene was placed on the chromosome in single copy or on a low-copy-number plasmid [3].

Chemical compound and disease context of tsr

• In E. coli AW660 (tsr tar trg), which lacks the known methyl-accepting chemotaxis proteins, chemotaxis was normal to oxygen and to substrates of the phosphotransferase system such as D-mannose, D-glucose, and N-acetyl-D-glucosamine [8].
• All of the inducers are chemotactic repellents for E. coli, and they are detected by the tsr gene product (with the possible exceptions of dimethyl sulfoxide and methylpyrrolidinone, whose modes of detection are not known) [9].
• Thermosensing properties of Escherichia coli tsr mutants defective in serine chemoreception [10].
• Using null mutations in the genes coding for the two major methyl-accepting proteins (tsr and tar), we identified the gene products among the membrane proteins of Escherichia coli visualized on one- and two-dimensional gels [11].
• The tse (taxis to serine) gene of E. aerogenes also complements an E. coli tsr mutant; the tas (taxis to aspartate) gene of E. aerogenes complements the defect in aspartate taxis, but not the defect in maltose taxis, of an E. coli tar mutant [12].

Biological context of tsr

• Correlation of this protein sequence data with the nucleotide sequence of the tsr gene [Boyd, A., Kendall, K. & Simon, M.I. (1983) Nature (London) 301, 623-626] suggests that CheB-dependent modification of MCPI is the enzymatic deamidation of glutamine to methyl-accepting glutamic acid [13].
• We then introduced either an aer or tsr mutation into each mutant to create two sets of electron transport mutants [14].
• Strain HCB326 (cheAWRBYZ tar tap tsr trg::Tn10), which was deficient in all chemotaxis components except the switch and motor, was transformed with the pCK63 plasmid (ptac-cheY+) [15].
• The conclusion that methylation generates multiplicity was supported by the results of experiments in which the tsr product was synthesized in mutant bacteria defective in specific chemotaxis functions concerned with methylation or demethylation of MCPs [2].
• The apparent transcription start site of the E. coli tsr gene was determined in both E. coli and C. crescentus, and we found that in both backgrounds the promoter used conforms to the consensus sequence for the promoters of the flagellar and chemosensory genes of Bacillus subtilis and E. coli [3].

Anatomical context of tsr

• The prevalence and function of four chemoreceptors, Tsr, Tar, Trg, and Tap, were determined for a collection of uropathogenic, fecal-commensal, and diarrheagenic Escherichia coli strains. tar and tsr were present or functional in nearly all isolates [16].
• Low concentrations of L-[14C]serine specifically bound to wild-type membranes with a Km of 5 microM; in contrast, there was greatly decreased binding to vesicles prepared from the new mutants or from the tsr mutant AW518 [17].
• The relationship between the chemoreceptor and thermoreceptor functions of Tsr was examined in five tsr mutants with altered serine detection thresholds [10].

Associations of tsr with chemical compounds

• MCPI, the product of the tsr gene, accepts methyl groups at multiple sites that are located on two tryptic peptides, denoted K1 and R1 [13].
• Typhimurium with mutations in the tsr (serine chemotaxis receptor protein) or oxrA (transcriptional regulator of anaerobic metabolism) genes did not inhibit colonisation [18].
• Pleiotropic aspartate-taxis mutants (tar) showed normal thermoresponse but pleiotropic serine-taxis mutants (tsr) showed decreased or almost no thermoresponse [19].

Regulatory relationships of tsr

• Thus, the presence of a cheX defect blocked the stimulus-elicited appearance of faster migrating forms of the tsr product; conversely, the presence of a cheB defect resulted in a pronounced shift toward these forms in the absence of a chemotactic stimulus [2].

Analytical, diagnostic and therapeutic context of tsr

• Unlike tsr null mutants, cheD strains are generally nonchemotactic, dominant in complementation tests, and exhibit a pronounced counterclockwise bias in flagellar rotation [20].

References