The metabolic affects of overexpression of Gcr1p transcription factor in Saccharomyces cerevisiae


Thesis Type: Postgraduate

Institution Of The Thesis: Bursa Uludağ University, Fen Bilimleri Enstitüsü, Moleküler Biyoloji ve Genetik, Turkey

Approval Date: 2015

Thesis Language: Turkish

Student: MEVLÜT ULAŞ

Supervisor: Sezai Türkel

Abstract:

Gycerol, trehalose and ethanol are important industrial metabolites produced from glycolytic pathway in Saccharomyces cerevisiae. The most important transcription factor that activates the transcription of the glycolitic enzyme encoding genes is GCR1. In GCR1 deletion mutant yeasts, the levels of glycolitic enyzmes decrease to 1-3% of the normal, wild type levels. GCR1 mutant Saccharomyces cerevisiae strains grow very slow in the glucose medium. GCR1 gene is transcribed at low levels. Gcr1p is also involved in the transcriptional activation of HXT genes that are involved in glucose transport. In this study, GCR1 gene is expressed from CUP1 promoter on the high copy yeast expression vector. Both the wild type and the metabolic mutant S. cerevisiae strains were used in the study. The effects of GCR1 over-expression on the growth rate, glucose consumption and reserve carbohydrate metabolism was investigated. Results of this study indicates that GCR1 over-expression increases the growth rate of the wild type yeast strain. Gcr1p over-production also alters the glucose consumption rate, biosynthesis of trehalose, glycogen, and glycerol, depending on the genetic structure of the yeast strains. Nonetheless, our results indicated that GCR1 over-expression has no effect on the ethanol biosynthesis in yeast.