Flan
Mostrando 13-23 de 23 artigos, teses e dissertações.
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13. Genetic switching in the flagellar gene hierarchy of Caulobacter requires negative as well as positive regulation of transcription.
Caulobacter crescentus flagellar (fla, flb, or flg) genes are periodically expressed in the cell cycle and they are organized in a regulatory hierarchy. We have analyzed the genetic interactions required for fla gene expression by determining the effect of mutations in 30 known fla genes on transcription from four operons in the hook gene cluster. These resu
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14. Two classes of region III flagellar genes in Escherichia coli.
We infected various nonflagellated mutants of Escherichia coli with fla-transducing phages and followed the kinetics of the appearance of motility. Our analysis revealed two distinct classes of region III fla genes. Class II fla genes (hag, flaD) functioned 15 min later than class I fla genes (flaN, flaB, flaC, flaO, flaA, flbD, flaQ, flaP) in flagellar morp
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15. Physical mapping and complementation analysis of transposon Tn5 mutations in Caulobacter crescentus: organization of transcriptional units in the hook gene cluster.
Using the cloned DNA from the hook protein gene region of Caulobacter crescentus ( Ohta et al., Proc. Natl. Acad. Sci. U.S.A. 79:4863-4867, 1982), we have identified and physically mapped 19 Tn5-induced and 2 spontaneous insertion mutations to this region of the chromosome. These nonmotile mutants define a major cluster of fla genes that covers approximately
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16. Identification of the promoter and a negative regulatory element, ftr4, that is needed for cell cycle timing of fliF operon expression in Caulobacter crescentus.
The fliF operon of Caulobacter crescentus, which was previously designated the flaO locus, is near the top of the flagellar-gene regulatory hierarchy, and it is one of the earliest transcription units to be expressed in the cell cycle. In this report, we have identified two cis-acting sequences that are required for cell cycle regulation of fliF transcriptio
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17. Subdivision of flagellar genes of Salmonella typhimurium into regions responsible for assembly, rotation, and switching.
Three flagellar genes of Salmonella typhimurium (flaAII.2, flaQ, and flaN) were found to be multifunctional, each being associated with four distinct mutant phenotypes: nonflagellate (Fla-), paralyzed (Mot-), nonchemotactic (Che-) with clockwise motor bias, and nonchemotactic (Che-) with counterclockwise motor bias. The distribution of Fla, Mot, and Che muta
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18. Positioning Flagellar Genes in Escherichia coli by Deletion Analysis
Two methods were devised to select a series of overlapping deletion mutations carried on episomal elements in Escherichia coli. The deletions were then used in an analysis of (i) the relative position on the genome of previously described mutant loci in the flagellar genes, (ii) the relative position of a newly defined cistron, flaN, and (iii) the orientatio
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19. Regulation of expression of the flagellin gene (hag) in Escherichia coli K-12: analysis of hag-lac gene fusions.
Previous studies have defined 28 genes necessary for the synthesis of the flagellar apparatus of Escherichia coli K-12. This study analyzed the influence of the flagellar genes on the expression of the hag gene (structural gene for flagellin). To this end, a hag::Mu d(Apr lac) mutant which had the lac genes fused to the promoter of the hag gene was construct
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20. Incomplete flagellar structures in Escherichia coli mutants.
Escherichia coli mutants with defects in 29 flagellar genes identified so far were examined by electron microscopy for possession of incomplete flagellar structures in membrane-associated fractions. The results are discussed in consideration of the known transcriptional interaction of flagellar genes. Hook-basal body structures were detected in flaD, flaS, f
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21. Definition of Additional Flagellar Genes in ESCHERICHIA COLI K12
Twenty-nine flagellar genes in Escherichia coli K12 have previously been assigned to three regions of the genome. Flagellar region I is located between pyrC and ptsG, region II between aroD and uvrC, and region III between uvrC and his. In this study, flagellar mutants in Escherichia coli K12 were obtained by selection for resistance to the flagellotropic ph
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22. FlbD of Caulobacter crescentus is a homologue of the NtrC (NRI) protein and activates sigma 54-dependent flagellar gene promoters.
The periodic transcription of flagellar genes in the Caulobacter crescentus cell cycle is controlled, in part, by their organization in a regulatory hierarchy. The flbG (hook operon), flaN, and flagellin gene operons, which are at the lowest levels of the hierarchy and expressed late in the cell cycle, contain Ntr-like promoters. We report that flbD, one of
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23. Fusions of flagellar operons to lactose genes on a mu lac bacteriophage.
Previous studies have defined 29 genes necessary for synthesis of the Escherichia coli flagellar apparatus. This study analyzed the transcriptional control of flagellar genes, using Mu d (Apr lac) phage to generate flagellar mutants by insertion. These mutants contained operon fusions of flagellar genes to the lac genes of the Mu d phage and allowed the meas