The “Crabtree Effect” is the fermentation of yeast cells in the presence of oxygen by

suppressing mitochondrial genes required for oxidative respiration. As a result of

fermentation, a high rate of alcohol and acetate is produced, while a low rate of ATP is

produced. Yeast species having crabtree effect are called crabtree positive (e.g.

Saccharomyces cerevisiae) and yeast species without crabtree effect are called crabtree

negative (e.g. Klyveromyces lactis). Crabtree negative yeast strains are usually utilized

heterologous protein production in the industrial field, while crabtree pozitive yeast strains

have been used to understand the cancer metabolism, especially in recent years. The genes

encoding enzymes related to glycolytic pathway in S. cerevisiae yeast cells are controlled by

Gcr1p, encoded by GCR1 (GlyColysis Regulaotr 1). Gcr1p binds to 5'-CTTCC-3' (CT box)

consensus sequences located in the promoter regions of glycolytic genes and activates their

transcription. In addition, Gcr1p also controls the transcription of the Alcohol Dehydrogenase

(ADH) and Pyruvate Decarboxylase (PDH) genes after pyruvate poduction. Therefore, the

aim of the study was to investigate by comparing the similarities and differences Gcr1p in S.

cerevisiae with GCR1 promoter, GCR1 gene and Gcr1p sequence analysis in whole genome

sequenced crabtree positive and negative yeast strains. For this purpose, of S. cerevisiae

GCR1 nucleotide sequence and the Gcr1p amino acid sequences were downloaded as “.fasta”

format using the SGD (https://www.yeastgenome.org) database and saved. Yeast strains showing similarity to the S. cerevisiae Gcr1 protein sequence were determined using the

BLASTp-NCBI program on the SGD database. Crabtree positive and negative yeast strain

were defined, and the whole genome data of these strains were downloaded from NCBIGenome

Database (https://www.ncbi.nlm.nih.gov/genome/). After that, the gene, amino acid

and possible promoter (~1000bp) sequences of Gcr1p and Gcr1-like proteins of carbtree

positive and negative yeast strains were determined and saved as “.fasta” format. Gcr1p and

Gcr1-like protein amino acid sequences, amino acid sequences of the leucine-zipper region

and DNA binding region of crabtree positive and negative yeast strains were aligned using the

Blossum62 parameter in the MEGA-X program and amino acid similarities were analyzed.

Gcr1p and Gcr1-like protein amino acid sequences and amino acid sequences of the leucinezipper

region and DNA binding region of crabtree positive and negative yeast strains were

aligned using the Blossum62 parameter in the MEGA-X program and amino acid similarities

were examined. The possible promoter sequences of the GCR1 gene of yeast strains were

mapped utilized the Chromatin Folding v2 program (www.dna.ccs.tulane.edu), and the

possible localization of the CT box was determined. As a result of this study, 32 different

yeast species matched to S. cerevisiae Gcr1p were determined and yeast strains were

seperated into crabtree positive and negative. Totally 10 yeast species crabtree positive, 5

yeast species crabtree negative were obtained. As a consequence of Gcr1p sequence analysis,

it is shown that the gene regions identified as “gene with unknown fonction” in some yeast

spesies are encoded Gcr1p or Gcr1-like proteins.