Non-histon proteinleri ve transkripsiyon mediatörlerinin HXT genleri transkripsiyonunun düzenlenmesine etkilerinin analizi
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Date
2005-08-15
Authors
Güzelvardar, Sinem
Journal Title
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Publisher
Uludağ Üniversitesi
Abstract
Saccharomyces cerevisiae’da HXT2 ve HXT4 genleri glukozun alımı için gerekli olan iki farklı transporter kodlar. Bu araştırmada mutant maya suşları kullanılarak, kromatin yapısını değiştiren faktörlerin HXT2 ve HXT4 genleri transkripsiyonuna etkileri araştırıldı. HXT2 ve HXT4 genlerinin transkripsiyonal aktivasyonlarının tamamen non-histon proteinleri olan Nhp6A/B’ye bağlı olduğu bulundu. ∆nhp6A/B mutant maya suşunda HXT2 ve HXT4 genleri transkripsiyonunda yaklaşık olarak 5-10 kat azalma belirlendi. Bu sonuçlara ek olarak, ∆nhp10 mutantında HXT2 transkripsiyonunda 2 katlık bir azalmanın olması, Nhp10p’nin HXT2 geni transkripsiyonunun aktivasyonu için gerekli olabileceğini gösterdi. SAGA kompleksinin HXT2 ve HXT4 transkripsiyonlarına etkileri ∆spt7 mutant maya suşu kullanılarak araştırıldı. ∆spt7 mutant maya suşunda HXT4 geni transkripsiyonunun yaklaşık olarak 20 kat azaldığı bulundu. HXT4’den farklı olarak, HXT2 geni transkripsiyonunun ∆spt7 mutantında sadece 2 kat azaldığı bulundu. Maya mediatör kompleksinin HXT2 ve HXT4 genleri transkripsiyonuna etkileri de analiz edildi. HXT4’ün hem bazal hemde aktive edilmiş transkripsiyonunun ∆med2 mutant suşunda 10-15 kat azaldığı bulundu. Fakat HXT2 transkripsiyonu ∆med2 mutantında sadece 2 kat azaldı. Diğer bir mediatör olan Srb10’un HXT2 ve HXT4 genleri transkripsiyonuna önemli bir etkisi olmadığı bulundu. Bu sonuçlar, daha önceden belirlenen transkripsiyon faktörlerine ek olarak HXT2 ve HXT4 genlerinin transkripsiyonlarının SAGA kompleksi, Nhp6A/B ve Med2p ile düzenlendiğini gösterdi.
In the yeast Saccharomyces cerevisiae, HXT2 and HXT4 genes encodes two different glucose transporters which are required for the glucose uptake. In this research, the effects of chromatin modifying factors on the HXT2 and HXT4 genes transcriptions were investigated by using mutant yeast strains. It was found that transcriptional activation of HXT2 and HXT4 are completely depends on the non-histone proteins Nhp6A/B. Approximately 5-10 fold decrease was determined in the transcription of HXT2 and HXT4 genes in ∆nhp6A/B mutant yeast cells. In addition to this results, 2 fold decrease in the transcription of HXT2 in ∆nhp10 mutation indicated that Nhp10 may be required for the activation of HXT2 genes. The effects of SAGA complex on the HXT2 and HXT4 transcriptions were investigated using ∆spt7 mutant yeast strain. It was found that the transcription of HXT4 decreased approximately 20-fold in ∆spt7 mutant yeast strain. Unlike HXT4 transcription, HXT2 transcription decreases 2-fold in ∆spt7 mutants. The effects of yeast mediator complex on the transcription of HXT2 and HXT4 were also analysed. It is found that both basal and activated transcription of HXT4 decrease 15 fold in the ∆med2 mutant yeast strain. But, transcription of HXT2 decreased only 2-fold in ∆med2 mutant strain. It was also found that, Srb10p, which is another mediator protein, doesn’t have any significant effect on HXT2 and HXT4 genes transcription. These results indicated that the transcription of HXT2 and HXT4 genes are regulated by SAGA complex, Nhp6A/B and Med2p, in addition to previously identified regulatory transcription factors.
In the yeast Saccharomyces cerevisiae, HXT2 and HXT4 genes encodes two different glucose transporters which are required for the glucose uptake. In this research, the effects of chromatin modifying factors on the HXT2 and HXT4 genes transcriptions were investigated by using mutant yeast strains. It was found that transcriptional activation of HXT2 and HXT4 are completely depends on the non-histone proteins Nhp6A/B. Approximately 5-10 fold decrease was determined in the transcription of HXT2 and HXT4 genes in ∆nhp6A/B mutant yeast cells. In addition to this results, 2 fold decrease in the transcription of HXT2 in ∆nhp10 mutation indicated that Nhp10 may be required for the activation of HXT2 genes. The effects of SAGA complex on the HXT2 and HXT4 transcriptions were investigated using ∆spt7 mutant yeast strain. It was found that the transcription of HXT4 decreased approximately 20-fold in ∆spt7 mutant yeast strain. Unlike HXT4 transcription, HXT2 transcription decreases 2-fold in ∆spt7 mutants. The effects of yeast mediator complex on the transcription of HXT2 and HXT4 were also analysed. It is found that both basal and activated transcription of HXT4 decrease 15 fold in the ∆med2 mutant yeast strain. But, transcription of HXT2 decreased only 2-fold in ∆med2 mutant strain. It was also found that, Srb10p, which is another mediator protein, doesn’t have any significant effect on HXT2 and HXT4 genes transcription. These results indicated that the transcription of HXT2 and HXT4 genes are regulated by SAGA complex, Nhp6A/B and Med2p, in addition to previously identified regulatory transcription factors.
Description
Keywords
Transkripsiyon, Nükleozom, Glukoz transportu, HXT genleri, S. cerevisia, Kromatin faktörleri, Transcription, Nucleosome, Glucose transport, HXT genes, Chromatin factors
Citation
Güzelvardar, S. (2005). Non-histon proteinleri ve transkripsiyon mediatörlerinin HXT genleri transkripsiyonunun düzenlenmesine etkilerinin analizi. Yayınlanmamış yüksek lisans tezi. Uludağ Üniversitesi Fen Bilimleri Enstitüsü.