Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 2Citation - Scopus: 2Identification of Novel Arsenic Resistance Genes in Yeast(Wiley, 2022) Işık, Esin; Balkan, Çiğdem; Karl, Vivien; Karakaya, Hüseyin Çağlar; Hua, Sansan; Rauch, Sebastien; Tamás, Markus J; Koç, AhmetArsenic is a toxic metalloid that affects human health by causing numerous diseases and by being used in the treatment of acute promyelocytic leukemia. Saccharomyces cerevisiae (budding yeast) has been extensively utilized to elucidate the molecular mechanisms underlying arsenic toxicity and resistance in eukaryotes. In this study, we applied a genomic DNA overexpression strategy to identify yeast genes that provide arsenic resistance in wild-type and arsenic-sensitive S. cerevisiae cells. In addition to known arsenic-related genes, our genetic screen revealed novel genes, including PHO86, VBA3, UGP1, and TUL1, whose overexpression conferred resistance. To gain insights into possible resistance mechanisms, we addressed the contribution of these genes to cell growth, intracellular arsenic, and protein aggregation during arsenate exposure. Overexpression of PHO86 resulted in higher cellular arsenic levels but no additional effect on protein aggregation, indicating that these cells efficiently protect their intracellular environment. VBA3 overexpression caused resistance despite higher intracellular arsenic and protein aggregation levels. Overexpression of UGP1 led to lower intracellular arsenic and protein aggregation levels while TUL1 overexpression had no impact on intracellular arsenic or protein aggregation levels. Thus, the identified genes appear to confer arsenic resistance through distinct mechanisms but the molecular details remain to be elucidated.Article Citation - WoS: 13Citation - Scopus: 17Characterization of Antimicrobial Activities of Olive Phenolics on Yeasts Using Conventional Methods and Mid-Infrared Spectroscopy(Springer, 2019) Canal, Canan; Özen, Banu; Baysal, Ayşe HandanOlive fruit is very rich in terms of phenolic compounds. Antimicrobial activities of various phenolic compounds against bacteria and fungi are well established; however, their effects on yeasts have not been examined. Aim of this study was to investigate the antimicrobial effects induced by olive phenolic compounds, including tyrosol, hydroxytyrosol, oleuropein, luteolin and apigenin against two yeast species, Aureobasidium pullulans and Saccharomyces cerevisiae. For this purpose, yeasts were treated with various concentrations (12.5-1000ppm) of phenolic compounds and reduction in yeast population was followed with optical density measurements with microplate reader, yeast colony forming units and mid-infrared spectroscopy. All phenolic compounds were effective on both yeasts, especially 200ppm and higher concentrations have significant antimicrobial activity; however, effects of lower levels depend on the type of phenolic compound. According to mid-infrared spectral data, significant changes were observed in 1200-900cm(-1) range corresponding to carbohydrates of yeast structure as a result of exposure to all phenolic compounds except tyrosol. Spectra of tyrosol and luteolin treated yeasts also showed changes in 1750-1500cm(-1) related to amide section and 3600-3000cm(-1) fatty acid region. Since phenolic compounds from olives were effective against yeasts, they could be used in food applications where yeast growth showed problem. In addition, FTIR spectroscopy could be successfully used to monitor and characterize antimicrobial activity of phenolic compounds on yeasts as complementary to conventional microbiological methods.Article Citation - WoS: 33Citation - Scopus: 40Characterization of Two Genes Encoding Metal Tolerance Proteins From Beta Vulgaris Subspecies Maritima That Confers Manganese Tolerance in Yeast(Springer Verlag, 2013) Erbaşol, Işıl; Bozdağ, Gönensin Ozan; Koç, Ahmet; Pedas, Pia; Karakaya, Hüseyin ÇağlarManganese (Mn2+) is an essential micronutrient in plants. However increased Mn2+ levels are toxic to plant cells. Metal tolerance proteins (MTPs), member of cation diffusion facilitator protein (CDF) family, have important roles in metal homeostatis in different plant species and catalyse efflux of excess metal ions. In this study, we identified and characterized two MTP genes from Beta vulgaris spp. maritima (B. v. ssp. maritima). Overexpression of these two genes provided Mn tolerance in yeast cells. Sequence analyses displayed BmMTP10 and BmMTP11as members of the Mn-CDF family. Functional analyses of these proteins indicated that they are specific to Mn2+ with a role in reducing excess cellular Mn2+ levels when expressed in yeast. GFP-fusion constructs of both proteins localized to the Golgi apparatus as a punctuated pattern. Finally, Q-RT-PCR results showed that BmMTP10 expression was induced threefold in response to the excess Mn2+ treatment. On the other hand BmMTP11 expression was not affected in response to excess Mn2+ levels. Thus, our results suggest that the BmMTP10 and BmMTP11 proteins from B. v. ssp. maritima have non-redundant functions in terms of Mn2+ detoxification with a similar in planta localization and function as the Arabidopsis Mn-CDF homolog AtMTP11 and this conservation shows the evolutionary importance of these vesicular proteins in heavy metal homeostatis among plant species.Article Citation - WoS: 20Citation - Scopus: 20Genome-Wide Identification of Genes That Play a Role in Boron Stress Response in Yeast(Elsevier Ltd., 2011) Uluışık, İrem; Kaya, Alaattin; Ünlü, Ercan Selçuk; Avşar, Kadir; Karakaya, Hüseyin Çağlar; Yalçın, Talat; Koç, AhmetBoron is an essential micronutrient for plants and it is either necessary or beneficial for animals. Studies identified only few genes related to boron metabolism thus far and details of how boron is imported into cells and used in cell metabolism are largely unknown. In order to identify genes that play roles in boron metabolism, we screened the entire set of yeast haploid deletion mutants and identified 6 mutants that were resistant to toxic levels of boron, and 21 mutants that were highly sensitive to boron treatment. Furthermore, we performed a proteomic approach to identify additional proteins that are significantly up-regulated by boron treatment. Our results revealed many genes and pathways related to boron stress response and suggest a possible link between boron toxicity and translational control.Article Citation - WoS: 7Citation - Scopus: 7The Roles of Thiol Oxidoreductases in Yeast Replicative Aging(Elsevier Ltd., 2010) Hacıoğlu, Elise; Esmer, Işıl; Fomenko, Dmitri E.; Gladyshev, Vadim N.; Koç, AhmetThiol-based redox reactions are involved in the regulation of a variety of biological functions, such as protection against oxidative stress, signal transduction and protein folding. Some proteins involved in redox regulation have been shown to modulate life span in organisms from yeast to mammals. To assess the role of thiol oxidoreductases in aging on a genome-wide scale, we analyzed the replicative life span of yeast cells lacking known and candidate thiol oxidoreductases. The data suggest the role of several pathways in controlling yeast replicative life span, including thioredoxin reduction, protein folding and degradation, peroxide reduction, PIP3 signaling, and ATP synthesis. © 2010 Elsevier Ireland Ltd.