Banca de DEFESA: PRISCILLA OLIVEIRA GIL

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : PRISCILLA OLIVEIRA GIL
DATE: 19/10/2022
TIME: 13:00
LOCAL: meet.google.com/srf-pzxy-gva
TITLE:

ENTEROCIN B: EXPRESSION, PURIFICATION, CHARACTERIZATION AND ANALYSIS OF ITS ANTIFUNGAL PROFILE IN Candida STRAINS sp.

KEY WORDS:

Enterococcus, Enterocin B, Bioinformatic, Candidiasis.

PAGES: 78
BIG AREA: Ciências Biológicas
AREA: Bioquímica
SUMMARY:

Enterocins are a group of bacteriocins secreted by bacteria of the genus Enterococcus sp., which have antimicrobial, antiviral and antitumor activities well documented in the literature; however, few studies describe the anti-candida activity of these enterocins. Despite their probiotic characteristic, and their wide use in the industry against food spoilage, the feasibility of inserting enterococci in food has been ruled out due to the increased occurrence of virulence factors in these strains. An excellent approach to solving this problem is to express enterocins heterologously. In this work, Enterococcus faecium Enterocin B was characterized by bioinformatics tools, expressed and purified from E. coli BL21(DE3) and ArcticExpress cells in order to verify its solubility during expression. Finally, Enterocin B was tested for its antifungal effect on antifungal resistant Candida albicans and Candida glabrata reference strains. The results showed a difference in the tertiary structure when compared to the literature. The structure analyzed in this work showed two a-helix regions, while in the literature, Enterocin B showed four a-helix regions. However, the results of physicochemical predictions such as amount of amino acids (53), theoretical pI (9.25), molecular weight (5.4 kDa), amphipacity, among others, corroborate with results published by other authors. Large-scale heterologous expression was performed in ArcticExpress cells due to the partially soluble expression of the peptide, because in BL21 (DE3) cells, expression occurred entirely in the form of inclusion bodies. The in vitro results showed that Enterocin B was not able to inhibit the growth of Candida albicans and Candida glabrata strains at concentrations of 250 and 500 µg/mL, respectively, in the MIC assay. A likely hypothesis would be that the GB1 fusion protein, expressed together with Enterocin B to increase the stability and solubility of the peptide, might be preventing the initial interaction that occurs between the N-terminal portion of Enterocin B and the target cell membrane. Thus, additional tests involving Enterocin B, cleaved from the fusion protein, are necessary for a correct conclusion about the activity of this peptide against yeast strains.

BANKING MEMBERS:
Presidente - 1716846 - VANESSA FARIA CORTES
Externa ao Programa - 1742677 - JAQUELINE MARIA SIQUEIRA FERREIRA
Externa à Instituição - SIMONE DA FONSECA PIRES - IFSUDESTEMG