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Full-Text Articles in Molecular Biology

Cell Surface Adhesins, Exopolysaccharides And The Por (Type Ix) Secretion System Of Flavobacterium Johnsoniae, Abhishek Shrivastava May 2013

Cell Surface Adhesins, Exopolysaccharides And The Por (Type Ix) Secretion System Of Flavobacterium Johnsoniae, Abhishek Shrivastava

Theses and Dissertations

Flavobacterium johnsoniae, a member of the phylum Bacteroidetes, crawls rapidly over surfaces. Cell movement is thought to result from the action of the gliding motor, composed of Gld proteins, on the cell-surface adhesin SprB. Cells lacking SprB are partially defective in motility. Transposon mutagenesis of an sprB mutant resulted in the identification of remA, which encodes a motility adhesin that is partially redundant with SprB. Cells lacking SprB and RemA had more severe motility defects than did cells lacking just SprB. RemA moves on the cell-surface with a speed of 1 to 2 micrometer per sec, similar to SprB. RemA …


Quorum Sensing In Vibrios And Cross-Species Activation Of Bioluminescence Lux Genes By Vibrio Harveyi Luxr In An Arabinose-Inducible Escherichia Coli Expression System, Anne Marie Wannamaker May 2013

Quorum Sensing In Vibrios And Cross-Species Activation Of Bioluminescence Lux Genes By Vibrio Harveyi Luxr In An Arabinose-Inducible Escherichia Coli Expression System, Anne Marie Wannamaker

Theses and Dissertations

Bacterial bioluminescence is observed in over twenty known species, primarily in the family Vibrionaceae. However, only Vibrio fischeri and Vibrio harveyi bioluminescence expression mechanisms are well studied. In V. harveyi, expression of the lux operon is activated by the transcription factor LuxR (LuxRVH), resulting in bioluminescence. Homologs of LuxRVH in other Vibrio species have been shown to regulate transcription of a variety of genes. Three parallel quorum sensing pathways co-regulate the expression of LuxRVH. The first objective was to assess possible quorum sensing regulation of lux operon expression in V. cholerae, V. chagasii, …


Prolonged Glucose Deprivation Sensitizes Snf1 To Negative Regulation By Pka To Delay Entry Into Quiescence, Leah Bernadette Doughty May 2013

Prolonged Glucose Deprivation Sensitizes Snf1 To Negative Regulation By Pka To Delay Entry Into Quiescence, Leah Bernadette Doughty

Theses and Dissertations

AMPK, the fuel gauge of the cell, and its upstream kinase, LKB1, have been implicated in cancer prevention and stress response associated with energy exhaustion. In the yeast Saccharomyces cerevisiae, Snf1 is the ortholog of mammalian AMPK. In S. cerevisiae, Snf1 is activated by phosphorylation of its T–loop at Thr210, primarily by its upstream kinase Sak1, in absence of the preferred carbon source, glucose, or during some other stress responses. Cyclic AMP–dependent protein kinase A, PKA, is involved in nutrient signaling largely antagonistically to Snf1. Using yeast strains of the Sigma 1278b genetic background, which have a high basal level …