Show simple item record

dc.contributor.authorLOEWY, ZVI G.
dc.identifier.citationSource: Dissertation Abstracts International, Volume: 48-10, Section: B, page: 2879.
dc.description.abstractCaulobacter crescentus synthesizes a single polar flagellum at a specific time in its cell cycle. The synthesis and assembly of the flagellum, as well as the chemotaxis machinery, depends on a complex regulatory cascade that controls the time of synthesis as well as the positioning of a large number of flagellar and chemotaxis proteins within the cell. The expression of one of the flagellar genes, flgJ, which encodes the 29 K flagellin protein, has been studied in an attempt to elucidate the mechanism of temporal and spatial control. Immunoprecipitation analysis established the time of synthesis of the 29 K flagellin protein during the cell cycle. Nuclease S1 experiments showed that the initial appearance of flgJ message coincided with the onset of 29 K flagellin synthesis. Two approaches were undertaken to define the nature of this temporal regulation: (1) The flgJ gene was subcloned into a plasmid and mated into a Caulobacter strain deleted for flgJ. This analysis demonstrated that the timing of flgJ expression remained intact, and thus its cell cycle regulation was independent of its chromosomal location. (2) The flgJ promoter was fused to a promoterless neomycin phosphotransferase II (NPT II) gene. Results of these experiments suggested that the sequences 5{dollar}\sp\prime{dollar} to the structural gene determined the time of expression of flgJ. A series of 5{dollar}\sp\prime{dollar} deletions were constructed and fused to a reporter gene in an attempt to delineate the exact nucleotide sequences responsible for temporal control. Analysis of mutants in a wide spectrum of fla genes has revealed that their products affect in trans the level of flgJ expression, and that this effect is independent of timing.;To study the positioning and segregation of the 29 K flagellin protein, a number of chimeric constructs were made that encoded portions of the flgJ structural gene fused to different reporter genes. These constructions were all mated into Caulobacter, and the segregation patterns of the reporter proteins and the fusion proteins were determined. This analysis has demonstrated that the control of positioning of the protein is dependent on the protein coding region and independent of the regulatory sequences responsible for its temporal control.
dc.publisherProQuest Dissertations & Theses
dc.subjectMolecular biology.

Files in this item


There are no files associated with this item.

This item appears in the following Collection(s)

Show simple item record