Taxis
Mostrando 13-24 de 102 artigos, teses e dissertações.
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13. Identification and Characterization of Two Chemotactic Transducers for Inorganic Phosphate in Pseudomonas aeruginosa
Two chemotactic transducers for inorganic phosphate (Pi), designated CtpH and CtpL, have been identified in Pseudomonas aeruginosa. The corresponding genes (ctpH and ctpL) were inactivated by inserting kanamycin and tetracycline resistance gene cassettes into the wild-type genes in the P. aeruginosa PAO1 genome. Computer-assisted capillary assays showed that
American Society for Microbiology.
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14. Cloning and characterization of a Pseudomonas aeruginosa gene involved in the negative regulation of phosphate taxis.
Pseudomonas aeruginosa PAO1 exhibited a positive chemotactic response to P(i). The chemotactic response was induced by P(i) limitation. An alkaline phosphatase (AP) constitutive mutant showed a chemotactic response to P(i), regardless of whether the cells were starved for P(i). Sequence analysis and complementation studies showed that the P. aeruginosa phoU
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15. Phosphotransferase-System Enzymes as Chemoreceptors for Certain Sugars in Escherichia coli Chemotaxis
For D-glucose and analogs there are two distinct phosphotransferase enzymes II with different specificities. Transport and chemotaxis were studied in E. coli mutants having only one or the other of these two enzymes. It was found that the transport specificity of a given enzyme II correlates with taxis specificity, and mutational loss of an enzyme II abolish
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16. Structural features of methyl-accepting taxis proteins conserved between archaebacteria and eubacteria revealed by antigenic cross-reaction.
A number of eubacterial species contain methyl-accepting taxis proteins that are antigenically and thus structurally related to the well-characterized methyl-accepting chemotaxis proteins of Escherichia coli. Recent studies of the archaebacterium Halobacterium halobium have characterized methyl-accepting taxis proteins that in some ways resemble and in other
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17. Relationships between C4 dicarboxylic acid transport and chemotaxis in Rhizobium meliloti.
The relationship between chemotaxis and transport of C4 dicarboxylic acids was analyzed with Rhizobium meliloti dct mutants defective in one or all of the genes required for dicarboxylic acid transport. Succinate, malate, and fumarate were moderately potent chemoattractants for wild-type R. meliloti and appeared to share a common chemoreceptor. While dicarbo
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18. Behavioral responses of Escherichia coli to changes in redox potential.
Escherichia coli bacteria sensed the redox state in their surroundings and they swam to a niche that had a preferred reduction potential. In a spatial redox gradient of benzoquinone/benzoquinol, E. coli cells migrated to form a sharply defined band. Bacteria swimming out of either face of the band tumbled and returned to the preferred conditions at the site
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19. Evolution of chemotactic-signal transducers in enteric bacteria.
The methyl-accepting chemotactic-signal transducers of the enteric bacteria are transmembrane proteins that consist of a periplasmic receptor domain and a cytoplasmic signaling domain. To study their evolution, transducer genes from Enterobacter aerogenes and Klebsiella pneumoniae were compared with transducer genes from Escherichia coli and Salmonella typhi
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20. Properties of Mutants in Galactose Taxis and Transport
β-Methylgalactoside (mgl) permease mutants of Escherichia coli, which are defective in three genes, mglA, mglB, and mglC, were assayed for galactose taxis and galactose transport. The mglB product is the galactose-binding protein. Previous evidence, supported by our new findings, shows that the galactose-binding protein is the recognition component for gala
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21. Salt taxis in Escherichia coli bacteria and its lack in mutants.
Escherichia coli is attracted to a variety of salts. This attraction is highly reduced in mutants missing a known transducer, the methyl-accepting chemotaxis protein I; there is a smaller role for another transducer, the methyl-accepting chemotaxis protein II. We discuss the relation of salt taxis to osmotaxis.
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22. Aspartate and maltose-binding protein interact with adjacent sites in the Tar chemotactic signal transducer of Escherichia coli.
The Tar protein of Escherichia coli is a chemotactic signal transducer that spans the cytoplasmic membrane and mediates responses to the attractants aspartate and maltose. Aspartate binds directly to Tar, whereas maltose binds to the periplasmic maltose-binding protein, which then interacts with Tar. The Arg-64, Arg-69, and Arg-73 residues of Tar have previo
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23. Aromatic acids are chemoattractants for Pseudomonas putida.
A quantitative capillary assay was used to show that aromatic acids, compounds that are chemorepellents for Escherichia coli and Salmonella sp., are chemoattractants for Pseudomonas putida PRS2000. The most effective attractants were benzoate; p-hydroxybenzoate; the methylbenzoates; m-, p-, and o-toluate; salicylate; DL-mandelate; beta-phenylpyruvate; and be
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24. Electron acceptor taxis and blue light effect on bacterial chemotaxis.
Salmonella typhimurium and Escherichia coli from anaerobic cultures displayed tactic responses to gradients of nitrate, fumarate, and oxygen when the appropriate electron transport pathway was present. Such responses were named "electron acceptor taxis" because they are elicited by terminal electron acceptors. Mutant strains of S. typhimurium and E. coli wer