DSpace Community:http://hdl.handle.net/10362/35512013-05-24T03:06:56Z2013-05-24T03:06:56ZStudies on BolA and ribonuclease R: two important factors in the control of bacterial gene expressionMoreira, Ricardo Neveshttp://hdl.handle.net/10362/85562013-01-17T15:50:45Z2011-12-01T00:00:00ZTitle: Studies on BolA and ribonuclease R: two important factors in the control of bacterial gene expression
Authors: Moreira, Ricardo Neves
Abstract: The cellular concentration of a given RNA is the result of the balance
between its synthesis and degradation. Both DNA transcription and RNA decay
control the final levels of each protein in the cell. BolA is an Escherichia coli (E. coli)
protein, which induces changes in cell morphology when present in high levels.
BolA expression is regulated by two different promoters, a sigma 70 (σ70)
promoter responsible for the basal levels of this gene in exponential phase and a
sigma S (σS) gearbox promoter important in stress situations and stationary phase
of bacterial growth.
The first objective of this PhD work was to further characterize the
expression of the bolA gene. Based on bioinformatic analysis, we have identified
the H-NS protein as a putative transcriptional regulator of BolA. H-NS is a
relatively small protein, abundant in bacterial cells and is often compared to
eukaryotic histones due to its high affinity for DNA. In order to clarify the
possible role of H-NS in BolA transcription, we have constructed an hns E. coli
mutant. This mutant was compared to the wild type regarding the levels of bolA
mRNA transcript and in vitro DNA-protein interaction studies were performed.
These experiments allowed us to demonstrate that H-NS is able to down-regulate
the levels of bolA mRNA in exponential phase and bind to the bolA promoter
region. In addition, the DNA-protein interaction studies revealed that H-NS has a
special affinity to the curved bolA promoter region encompassing both bolA1p
and bolA2p promoters.(...)
Description: Dissertation presented to obtain the Ph.D degree in Biology2011-12-01T00:00:00ZFunctional studies on BolA and related genes: increasing the understanding of a protein with pleiotropic effectsGuinote, Inês Batistahttp://hdl.handle.net/10362/68652012-01-20T20:11:51Z2011-01-01T00:00:00ZTitle: Functional studies on BolA and related genes: increasing the understanding of a protein with pleiotropic effects
Authors: Guinote, Inês Batista
Abstract: BolA is a protein that is able to change bacterial shape, confer resistance against large antibiotic molecules and detergents, reduce permeability, change the equilibrium of the outer membrane porins, and it is even involved in biofilm formation. This protein has such pleiotropic effects, that its function has been very difficult to unravel. This was the starting point for the work of this dissertation. If bolA is responsible for global cellular changes that confer resistance to a multitude of stresses, it is imperative to obtain more molecular insights to increase the understanding of the role of BolA in cell physiology and survival.(...)
Description: Dissertation presented to obtain a Doctoral degree in Biology by Instituto de Tecnologia Química e Biológica2011-01-01T00:00:00ZFunctional and structural characterization of the RNase II-family of enzymesMatos, Rute Gonçalveshttp://hdl.handle.net/10362/61782011-10-27T15:30:25Z2011-09-01T00:00:00ZTitle: Functional and structural characterization of the RNase II-family of enzymes
Authors: Matos, Rute Gonçalves
Abstract: Ribonucleases (RNases) are ubiquitous and have a central role in the
control of gene expression. They are involved in the maturation of
functional RNAs as well as their degradation. RNases are also involved in
quality control mechanisms and are crucial to the recycling of
ribonucleotides, key cellular metabolites. Ribonucleases can be broadly
classified as endoribonucleases, which cleave at sites internal to the RNA,
or exoribonucleases, which remove nucleotides from either the 5' end or 3'
end of the RNA molecule. Enzymes from the RNase II-family of
exoribonucleases are present in all domains of life, and processively
degrade RNA in the 3’ to 5’ direction with a hydrolytic activity that releases
5’-nucleotide monophosphates. They play a crucial role in RNA metabolism
and have been shown to be required for normal growth and viability,
virulence, mitotic control and chloroplast biogenesis.(...)
Description: Dissertation presented to obtain a Doctoral Degree in Biology by Instituto
de Tecnologia Química e Biológica, Universidade Nova de Lisboa2011-09-01T00:00:00Z