ITQB: MMB - PhD Theses
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- Characterization of metalloproteins involved in oxidative stress and nitrogen cyclePublication . Farinha Fernandes, Susana Cristina; Folgosa, Filipe"The thesis entitled “Characterisation of metalloproteins involved in oxidative stress and nitrogen cycle: Atypical Flavodiiron Proteins and Hydroxylamine Oxidoreductases” was performed under the supervision of Dr. Filipe Folgosa, in the Functional Biochemistry of Metalloenzymes Laboratory at Instituto de Tecnologia Química e Biológica António Xavier (ITQB), from Nova University of Lisbon. This thesis is divided into three parts: Part I is the general introduction, which is itself divided into five sections: i) The nitrogen cycle, ii) Anammox bacteria, iii) Oxygen and reactive oxygen species (ROS), iv) Nitric oxide, and v) Flavodiiron Proteins (FDPs).(...)"
- Metalloenzymes in microbial defence mechanisms against oxygen and nitric oxidePublication . Martins, Maria Santos Carlos; Teixeira, Miguel; Folgosa, Filipe"Oxygen, nitric oxide and their derived species play key roles in life. Whereas O2 is essential in many organisms to survive, others use NO as defence mechanisms against pathogens. For example, the human immune system releases NO and H2O2, leading to the inhibition of multiple metabolic microbial processes. Flavodiiron proteins (FDPs) constitute a widespread family of enzymes present in all life domains with a crucial role in O2/ROS and/or NO detoxification, through the reduction of these species either to H2O or N2O, respectively. Therefore, flavodiiron proteins are key players in host-microbe interactions, from a host-pathogen strife viewpoint, and for survival of the human microbiota within challenging environments. (...) This thesis is focused on the study of FDPs mainly from human pathogens, in special Clostridia, the phylogenetic group with the larger diversity of FDPs’ classes and a widespread class of organisms among the human gut microbiome.(...)"
- Exploring Monotopic quinone reductasesPublication . Sousa, Filipe Medina; Pereira, Manuela M."Respiratory chains are groups of membrane bound enzymes which generate a membrane electrochemical potential by coupling an exergonic reaction to the translocation of charges (electrons or ions, H+ or Na+) across the membrane. Quinone reductases are considered the electron entry point of respiratory chains as they connect the different catabolic pathways from the soluble cytoplasmic reactions to the membrane bound respiratory chains. Quinone reductases can be classified in transmembrane or monotopic (placed at a single side of the lipid bilayer), with only the first ones directly contributing to the generation of the membrane electrochemical potential. Currently, 20 different “electron donor”:quinone oxidoreductase enzymatic activities have been described, from which 10 are monotopic.(...)"
- A molecular insight into the respiratory Alternative Complex IIIPublication . Calisto, Filipa Alexandra Gomes; Pereira, Manuela; Teixeira, Miguel"Life depends on a constant energy supply and conversion. Cells use energy from external sources, such as organic or inorganic compounds or light to sustain, grow and reproduce themselves. The energy from those sources has to be converted into energy forms useable for the different cellular processes, i.e., external energy is converted (transduced) to other forms such as adenosine triphosphate (ATP) and/or a transmembrane difference of the electrochemical potential.(...)"
- Disentangling the function and structural modularity of the membrane arm from respiratory complex IPublication . Castro, Paulo; Pereira, ManuelaLife depends on a great variety of energy transducing enzymes that establish and maintain a transmembrane difference of electrochemical potential. In this thesis, the presence of the different respiratory enzyme complexes in the several phyla of life was studied. The results highlight the remarkable diversity and modularity of respiratory chains, allowing the existence of life in a great array of environments. (...)
- THE ROLE OF THE FLAVODIIRON PROTEINS IN NITRIC OXIDE DETOXIFICATIONPublication . Vicente, João Filipe Bogalho"This dissertation portrays recent developments on the knowledge of a protein family whose once elusive role is presently clearer, although still prone to discussion. The family of Flavodiiron Proteins (FDPs), initially thought to protect anaerobes from oxygen exposure, have been proposed to have a role in nitric oxide detoxification. The main object of study of this dissertation, Escherichia coli Flavorubredoxin (FlRd) made a large contribution to establish this role. FlRd was the first member of the FDP family to be assigned as an NO reductase, followed by the demonstration of the same activity in other FDPs, although a role in oxygen scavenging by other FDP family members has to be considered.(...)"
- Supercomplexes of Prokaryotic Aerobic Respiratory Chains-Escherichia coli and Bacillus subtilis supramolecular assembliesPublication . Sousa, Pedro Miguel Ferreira; Melo, Ana; Teixeira, MiguelAerobic respiratory chains are composed of a series of membrane complexes that catalyze the electron transfer from reducing substrates to oxygen. The energy released through this process is used to translocate protons across the membranes, thus generating a proton motive force that activates F1FO-ATP synthase to synthesize ATP. The arrangement of these enzymes in the inner mitochondrial membrane is well characterized in mammalian mitochondria, where different sets of supramolecular assemblies, or supercomplexes, involving the majority of the respiratory complexes were described, reinforcing the idea of an operational solid state model wherein the oxidative phosphorylation processes are optimized.(...)
- Cyanobacterial and Protozoan Flavodiiron Proteins are nitric oxide and/or dioxygen reductasesPublication . Gonçalves, Vera Lúcia; Teixeira, MiguelThe present thesis focuses on the study of Flavodiiron Proteins (FDPs). The FDPs are dioxygen (O2) and/or nitric oxide (NO) reductases widely spread among prokaryotes and also found in eukaryotes, particularly anaerobic protozoa and photosynthetic organisms (from unicellular algae to higher plants).(...)
- Reductive scavenging of reactive oxygen species in prokaryotesPublication . Pinto, Ana Filipa CarapinhaThe purpose of this thesis is to contribute to a better understanding of systems involved in the scavenging of reactive oxygen species. The work focuses on an enzyme from the Rubrerythrin family that reduces hydrogen peroxide and one from the Superoxide Reductase family that reduces the superoxide anion. Both of these families are distributed widely across the three domains of life, Archaea, Bacteria and Eukarya, but are mainly found in anaerobic and microaerophilic prokaryotes.(...)
- Energy transduction by respiratory complex IPublication . Batista, Ana P.; Teixeira, Miguel; Pereira, Manuela M.The aim of the work presented in this dissertation was to provide a contribution to the understanding of the energy transducing mechanism of respiratory complex I. This enzyme is present in most bacteria and in all mitochondrial systems and it is characterized by its large number of subunits, its prosthetic groups (flavin and iron-sulfur centers), and its NADH:quinone oxidoreductase activity sensitive to specific inhibitors and coupled with charge translocation across the membrane.(...)