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SARIYAR AKBULUT, BERNA

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SARIYAR AKBULUT

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2015 - 20202
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Subject: ANTIBIOTICS ×

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    Potentiating the activity of berberine for Staphylococcus aureus in a combinatorial treatment with thymol
    (ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 2020) SARIYAR AKBULUT, BERNA; Aksoy, Cemile Selin; Avci, Fatma Gizem; Ugurel, Osman Mutluhan; Atas, Basak; Sayar, Nihat Alpagu; Akbulut, Berna Sariyar
    A plethora of natural products emerges as attractive molecules in the struggle against antibiotic resistance. These molecules impose their bioactivities not only alone but also in combinations as well, which further enhances their effects. Berberine is a well-known isoquinoline alkaloid with antibacterial activity. Unfortunately, it is readily extruded, which significantly reduces its efficacy and restricts its potential. Thymol is a monoterpenic phenol that exhibits different biological activities but its major effect is observed only at relatively high concentrations, which raises concern on cytotoxicity. The aim of the study was to potentiate the antibacterial activity of berberine, in a combination treatment with thymol in the opportunistic pathogen Staphylococcus aureus and understand the antibacterial mechanism of the combination treatment. The synergism of berberine and thymol was first established by the checkerboard assay. Then the antibacterial mechanism of the synergistic combination was explored by growth curves, biofilm formation assay, SEM observation, and RNA-Seq based transcriptomic profiling. Checkerboard assay showed that 32 mu g mL(-1) berberine and 64 mu g mL(-1) thymol was a synergistic combination, both concentrations below their cytotoxicity limits for many cells. 32 mu g mL(-1) berberine and 32 mu g mL(-1) thymol was sufficient to inhibit biofilm formation. SEM images confirmed the morphological changes on the structure of combination treated cells. The major finding of the combination treatment from the transcriptomic analysis was the repression in the expression of virulence factors or genes related to virulence factors. Apart from the particular changes related to the cell envelope, the majority of expressional changes seemed to be similar to berberine-treated cells or to be resulting from general stress conditions. The findings of this work showed that when thymol was used in combination with berberine, it enhanced the antibacterial activity of berberine in a synergistic manner. Furthermore, thymol could be considered as an antivirulence agent, disarming S. aureus cells.
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    Investigation of the in vivo interaction between beta-lactamase and its inhibitor protein
    (TUBITAK SCIENTIFIC & TECHNICAL RESEARCH COUNCIL TURKEY, 2015) SARIYAR AKBULUT, BERNA; Budeyri Gokgoz, Nilay; Yalaz, Simay; Avci, Naze Gul; Buldum, Gizem; Ozkirimli Olmez, Elif; Sariyar Akbulut, Berna
    The affinity of beta-lactamase inhibitory protein (BLIP) for TEM-1 beta-lactamase has raised hopes in the challenge of protein-based inhibitor discovery for beta-lactamase-mediated antibiotic resistance. Currently, the effect of the formation of the beta-lactamase:BLIP complex in vivo in beta-lactam resistant bacteria is an open question. The scarcity of information to the extent to which BLIP can impair beta-lactamase activity inside cells has urged us to assess the in vivo efficacy of BLIP as a potent beta-lactamase inhibitor. To this end, beta-lactamase and BLIP were coexpressed in Escherichia coli. Simultaneous expression of beta-lactamase and BLIP and the formation of the TEM-1 beta-lactamase: BLIP complex in the periplasmic space of E. coli were verified by electrophoretic and Western blot techniques. Growth profiles of the cells expressing both beta-lactamase and its protein inhibitor, complemented with beta-lactamase activity measurements, suggested that BLIP synthesis retarded cell growth and reduced beta-lactamase activity. Although co-expression of beta-lactamase and its protein inhibitor did not completely impair cell growth, the specificity of BLIP enabled it to bind beta-lactamase in the bacterial periplasm, regardless of the crowding components.