ITQB: SG - PhD Theses
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- Uncovering the intrinsic potential of Deinococcus species for arsenic bioremediationPublication . Gouveia, André G.; Romão, Célia; Carrondo, Maria Arménia"The Deinococcaceae family includes some of the most extensively studied radiaƟon-resistant bacteria, parƟcularly those of the genus Deinococcus. This thesis focuses on the stress-resistance mechanisms of Deinococcus radiodurans and Deinococcus indicus, with a parƟcular focus on their potenƟal applicaƟons in arsenic bioremediaƟon. While D. radiodurans is renowned for its resistance to radiaƟon, oxidaƟve damage, and desiccaƟon, its arsenic detoxiĮcaƟon capacity remains unexplored. In contrast, D. indicus is naturally resistant to arsenic but remains poorly studied. By integraƟng structural, molecular, and physiological analyses, this thesis provides novel insights into the adapƟve strategies and resistance mechanisms of these species.(...)"
- Unveiling the structural basis of the complex between the virulence factor SARS-CoV2 Nsp1 and the host DNA polymerase-alphaPublication . Salgueiro, Bruno; Romão, Célia; Moe, Elin; Matias, Pedro"The work presented in this dissertation focuses on studies of the Non-structural protein 1 (Nsp1) of SARS-CoV2 (Nsp1SARS-CoV2), identified as a major virulence factor causing Covid 19. Nsp1 is a small protein encoded by ORF1a/b and is found only in the a/b- Coronavirus (a/b-CoV) genera. SARS-CoV2 belongs to the b-CoV, and Nsp1 proteins from these genera consist of two structural domains: a globular N-terminal domain (NTD) and a flexible Cterminal domain (CTD), connected to the NTD by a loop (L) of approximately 28 amino acids. Despite the low sequence identity across Nsp1 proteins, they all share the same structural fold for the NTD.(...)"
- Deciphering molecular mechanisms of downstream steps in Base Excision Repair (BER)Publication . Pimenta Fernandes, Andreia Cecília; Moe, ElinDeinococcus radiodurans is a remarkable bacterium known for its extreme desiccation and radiation resistance. The mechanisms behind its extreme resistance are not well understood. However, an efficient DNA repair system, which includes Base Excision Repair (BER), is an important part of these mechanisms. BER repairs endogenous and exogenous damaged bases, abasic sites and strand breaks in DNA. To gain insights into the downstream mechanisms of BER and its potential impact on the extremophilic properties of D. radiodurans, we investigated the role of two key enzymes in this pathway, DNA polymerase I (DrPoll) and DNA ligase A (DrLigA).
- Unraveling the antioxidant protection mechanisms in the radiation resistant bacterium Deinococcus radioduransPublication . Pereira Dos Santos, Sandra Isabel; Romão, Célia Valente; Teixeira, Miguel Sepúlveda"Deinococcus radiodurans is a radiation resistant bacterium. For this reason, it has been a focus of several studies over the years. The aim has been to understand what makes this organism so resistant to different extreme conditions. Several protection mechanisms are present, such as enzymatic and non-enzymatic systems, namely Mn2+-Pi complexes. These mechanisms work synergistically, thereby conferring higher protection to this extraordinary organism.(...)"
- Unraveling structural features of flavodiiron proteins: a detailed structural insight for oxygen or nitric oxide reductionPublication . Borges, Patrícia Alexandra Teixeira; Romão, Célia V.; Frazão, Carlos"The work presented in this dissertation focuses on Flavodiiron Proteins (FDPs), a family of enzymes able to reduce oxygen and/or nitric oxide into water or non-toxic nitrous oxide. FDPs are widespread in prokaryotes and unicellular eukaryotes as well as in phototrophs, from cyanobacteria and unicellular algae to higher plants. The FDP minimal structural unit is composed of two domains: a metallo-β-lactamase- like domain at the N-terminal harbouring a diiron catalytic center and a flavodoxin-like domain at the C-terminal containing a non-covalently bound flavin mononucleotide (FMN). The diiron site is where the substrate reduction occurs while the FMN cofactor shuttles the electrons to this catalytic center. The two redox centers within the same monomer are too far away (~40 Å) to allow an efficient electron transfer between them. Therefore, the minimal functional unit of FDPs, consists of a homodimer with a “head-to-tail” arrangement, which brings close together (~6 Å) the diiron center of one monomer and the FMN cofactor of the neighbouring monomer. (...)"
- STRUCTURE-FUNCTION ANALYSIS OF MULTI-COPPER OXIDASESPublication . Silva, Catarina Isabel Simões Pires; Bento, IsabelDioxygen is a ubiquitous electron acceptor in aerobic biological systems, playing a vital role in many biological processes upon its activation and reduction. However, the precise routes through which such mechanisms occur are still poorly understood for many enzyme families. The work presented in this dissertation focuses on Multi-copper oxidases (MCOs), a family of enzymes able to couple the one-electron oxidation of a vast array of substrate molecules with the four-electron reduction of dioxygen to water.(...)