Molecular Biology and Genetics / Moleküler Biyoloji ve Genetik
Permanent URI for this collectionhttps://hdl.handle.net/11147/9
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Article Citation - WoS: 4Citation - Scopus: 3Boron Stress Signal Is Transmitted Through the Tor Pathway(Elsevier, 2023) Uluışık, İrem; Koç, AhmetAlthough boron is an essential element for many organisms, an excess amount of it can cause toxicity, and the mechanism behind this toxicity is not yet fully understood. The Gcn4 transcription factor plays a crucial role in the boron stress response by directly activating the expression of the boron efflux pump Atr1. More than a dozen transcription factors and multiple cell signaling pathways have roles in regulating the Gcn4 transcription factor under various circumstances. However, it is unknown which pathways or factors mediate boron signaling to Gcn4. Using the yeast Saccharomyces cerevisiae as a model, we analyzed the factors that converge on the Gcn4 transcription factor to assess their possible roles in boron stress signaling. Our findings show that the GCN system is activated by uncharged tRNA stress in response to boron treatment and that GCN1, which plays a role in transferring uncharged tRNAs to Gcn2, is necessary for the kinase activity of Gcn2. The SNF and PKA pathways were not involved in mediating boron stress, even though they interact with Gcn4. Mutations in TOR pathway genes, such as GLN3 and TOR1, abolished Gcn4 and ATR1 activation in response to boric acid treatment. Therefore, our study suggests that the TOR pathway must be functional to form a proper response against boric acid stress.Article Citation - WoS: 2Citation - Scopus: 2Characterization of the Beta1 Gene, Which Might Play a Role in Beta Vulgaris Subsp. Maritima Salt Tolerance(Türkiye Klinikleri Journal of Medical Sciences, 2017) Uysal, Özge; Çakıroğlu, Çiğdem; Koç, Ahmet; Karakaya, Hüseyin ÇağlarSalinity stress has a negative impact on plant growth, which affects homeostasis and productivity. The uptake of nonessential salt ions changes the osmotic balance of the cell and causes dehydration. Higher plants develop salt tolerance mechanisms to avoid dehydration. Sea beet (Beta vulgaris subsp. maritima) is a halophytic ancestor of cultivated sugar beet that displays salt stress tolerance. In this study, we screened a B. vulgaris subsp. maritima cDNA library in Saccharomyces cerevisiae strain Ab11c (ena1Δ, nha1/4Δ, nhx1Δ), which is deficient in sodium transport, to find sodium-detoxifying genes. We identified a cDNA construct, named BETA1, providing salt tolerance to yeast cells. This gene had no previously described function. Intracellular sodium measurements demonstrated no significant differences between yeast cells expressing BETA1 or a sham vector, suggesting that sodium was not effluxed in BETA1-expressing cells. Transcriptionally, BETA1 mRNA levels were induced immediately in leaves and later in the root system in response to the salt stress. Our results suggest that the BETA1 gene is part of the salt tolerance network in B. vulgaris subsp. maritima.Article Citation - WoS: 5Citation - Scopus: 4Characterization of a Cdna From Beta Maritima That Confers Nickel Tolerance in Yeast(Elsevier Ltd., 2014) Bozdağ, Gönensin Ozan; Kaya, Alaattin; Koç, Ahmet; Noll, Gundula A.; Prüfer, Dirk; Karakaya, Hüseyin ÇağlarNickel is an essential micronutrient due to its involvement in many enzymatic reactions as a cofactor. However, excess of this element is toxic to biological systems. Here, we constructed a cDNA library from Beta maritima and screened it in the yeast system to identify genes that confer resistance to toxic levels of nickel. A cDNA clone (NIC6), which encodes for a putative membrane protein with unknown function, was found to help yeast cells to tolerate toxic levels of nickel. A GFP fused form of Nic6 protein was localized to multivesicular structures in tobacco epidermal cells. Thus, our results suggest a possible role of Nic6 in nickel and intracellular ion homeostasis.Article Citation - WoS: 12Citation - Scopus: 12Identification of Respiratory Chain Gene Mutations That Shorten Replicative Life Span in Yeast(Elsevier Ltd., 2012) Hacıoğlu, Elise; Demir, Ayşe Banu; Koç, AhmetAging is the progressive accumulation of alterations in cells that elevates the risk of death. The mitochondrial theory of aging postulates that free radicals produced by the mitochondrial respiratory system contribute to the aging process. However, the roles of individual electron transfer chain (ETC) components in cellular aging have not been elucidated. In this study, we analyzed the replicative life span of 73 yeast deletion mutants lacking the genes of the mitochondrial electron transfer chain system, and found that nine of these mutants (δ nde1, δ tcm62, δ rip1, δ cyt1, δ qrc8, δ pet117, δ cox11, δ atp11, δ fmc1) had significantly shorter life spans. These mutants had lower rates of respiration and were slightly sensitive to exogenous administration of hydrogen peroxide. However, only two of them, δ nde1 and δ fmc1, produced higher amounts of intrinsic superoxide radicals in the presence of glucose compared to that of wild type cells. Interestingly, there were no significant alterations in the mitochondrial membrane potentials of these mutants. We speculate that the shorter life spans of ETC mutants result from multiple mechanisms including the low respiration rate and low energy production rather than just a ROS-dependent path. © 2011 Elsevier Inc.Article Citation - WoS: 5Citation - Scopus: 5Evidence for a Stabilizer Element in the Untranslated Regions of Drosophila Glutathione S-Transferase D1 Mrna(American Society for Biochemistry and Molecular Biology Inc., 2002) Akgül, Bünyamin; Tu, Chen-Pei D.The neighboring genes gstD1 and gstD21 share 70% sequence identity, gstD1 encodes a 1,1,1-trichloro-2,2-bis-(P-chlorophenyl)ethane dehydrochlorinase; gstD21, a ligandin. Both of their mRNAs are inducible by pentobarbital but otherwise behave very differently. Intact gstD21 mRNA is intrinsically labile, but becomes stabilized when separated from its native untranslated region (UTR). In contrast, whereas gstD1 mRNA is very stable in its entirety, without its native UTRs it becomes even more labile than that of gstD21. Decay patterns from four chimeric D1-D21 mRNAs, designed to reveal the individual importance of each molecular region to stability, strongly indicate the presence of destabilizing elements in the coding region ofgstD1 mRNA. Thus, the UTRs of this molecule must contain a dominant stabilizer element that overrides the destabilizing influence of the coding region and confers overall stability to the entire molecule. The suspected presence of such a stabilizer element in gstD1 mRNA extends a concept from mRNA metabolism in yeast and cultured mammalian cells to include a multicellular organism, Drosophila melanogaster. The complementary presence of destabilizing and stabilizer elements on the same mRNA reveals a regulatory mechanism by which an abundant mRNA can be further induced by a chemical stimulus, or otherwise be returned to normal levels during recovery.