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dc.contributor.authorCHAMPER, ROBERT JOHNS
dc.identifier.citationSource: Dissertation Abstracts International, Volume: 48-06, Section: B, page: 1598.
dc.description.abstractThe assembly of a functional flagellum in the bacterium Caulobacter crescentus requires the protein products of approximately 30 genes expressed in temporally-discrete and spatially-distinct manner. Our current understanding of this system has been limited by the fact that purified protein products are available for only about one-fifth of these genes. A genetically engineered transposon promoter probe, tn 5 -VB32, containing a promoter-less gene encoding neomycin phosphotransferase II (NPT II) was used to generate a series of non-motile ({dollar}fla\sp{lcub}-{rcub}{dollar}), kanamycin-resistant strains of C. crescentus. These transcription-fusions allow the expression of NPT II to be controlled by flagellar promoters, and thus questions of temporal regulation of flagellar genes can be addressed without the need to obtain purified protein products. The flagellar promoters accessed by Tn 5 -VB32 exhibited temporal regulation analogous to the known flagellar and chemotaxis gene products. The expression of NPT II in these mutants is read from a chimeric mRNA that initiates in a chromosomal fla promoter and continues through the inserted NPT II gene. Thus, temporal regulation is controlled by modulating either the initiation of transcription, or transcript turnover, at specific times in the cell cycle.;Epistatic interactions between the genes accessed by the promoter probe and other flagellar loci were studied in double fla mutants generated by transducing the promoter-probe mutations into spontaneously-derived second-site fla -mutant backgrounds. The synthesis of both natural fla gene products and the accessed NPT II was assayed in these strains using antisera to purified components of the flagellum and to purified NPT II. On the basis of these interactions, a trans -acting hierarchy of flagellar and chemotaxis gene expression is proposed.
dc.publisherProQuest Dissertations & Theses
dc.subjectMolecular biology.

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