Banca de QUALIFICAÇÃO: Gideane Mendes de Oliveira

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : Gideane Mendes de Oliveira
DATE: 24/02/2023
TIME: 14:30
LOCAL: Microsoft Teams
TITLE:

"Sterol C24-methyltransferases from the human pathogenic fungi Candida auris and Aspergillus fumigatus: structural, functional and inhibition studies aiming at the development of potential drugs."

KEY WORDS:

sterol C24-methyltransferases, gene erg6, Candida auris, Aspergillus fumigatus, human pathogenic fungi.

PAGES: 95
BIG AREA: Ciências Biológicas
AREA: Biologia Geral
SUMMARY:

Invasive fungal infections are a major cause of mortality in immunocompromised patients caused most by Candida and Aspergillus species. Candida auris species stand out with high mortality rates. Ergosterol is an essential lipid for the cell viability by being responsible for membrane fluidity and permeability. Cholesterol and ergosterol share the same metabolic pathway until the stage of zymosterol synthesis, from this point onwards they diverge and use different enzymes. The gene erg6 encodes a sterol C24-methyltransferase (SMT) that acts transferring C-24 methyl group converting zymosterol into fecosterol or acts in an alternative pathway converting lanosterol to eburicol. The SMT is a promising target because it is present in invasive fungi and absent in the human host. The soluble CauSMT (C. auris) and AfSMT (A. fumigatus) was purified by immobilized metal affinity chromatography. The effect of additives on the oligomeric state of the proteins was analyzed by size-exclusion chromatography and dynamic light scattering which showed a pentameric CauSMT and a tetrameric AfSMT. Thermal stability as a function of pH was analyzed by circular dichroism. This analysis demonstrated that CauSMT and AfSMT were more stable at an acid and neutral pH. The melting temperature of both enzymes at the most stable pH was 59 °C. Enzymatic assay showed that CauSMT has specificity for zymosterol and AfSMT uses the alternative pathway converting lanosterol to eburicol. Tomatidine exhibited antifungal activity against CauSMT. CauSMT and AfSMT crystals with S-adenosyl-L-methionine substrate were obtained under different crystallization conditions. Diffraction data collected at the Manacá LNLS/Sirius beamline with CauSMT crystals co-crystallized with S-adenosyl-L-methionine substrate showed resolutions of 7 to 8 Å. The refinement of these conditions is being carried out to obtain crystals that present diffractions with better resolutions, thus enabling the structural elucidation of the proteins of interest.

BANKING MEMBERS:
Presidente - 2222088 - ELIANE FERREIRA NORONHA
Externa ao Programa - 1657325 - LARISSA FERNANDES MATOS
Externa à Instituição - MARIA SUELI SOARES FELIPE - UCB
Externo ao Programa - 2128128 - NAPOLEAO FONSECA VALADARES