Saccharomyces cerevisiae, key role of MIG1 gene in metabolic switching: putative fermentation/oxidation.

Saccharomyces cerevisiae can utilize a wide range of carbon sources; however, in the presence of glucose the use of alternate carbon sources would be repressed. Several genes involved in the metabolic pathways exert these effects. Among them, the zinc finger protein, Mig1 (multicopy inhibitor of GAL gene expression) plays important roles in glucose repression of Saccharomyces cerevisiae. To investigate whether the alleviation of glucose effect would result in a switch to oxidative production pathway, MIG1 were disrupted in a haploid laboratory strain (2805) of S. cerevisiae. The impact of this disruption was studied under fully aerobic conditions when glucose was the sole carbon source. Our results showed that glucose repression was partly alleviated; i.e., ethanol, as a significant fermentation marker, and acetate productions were respectively decreased by 14.13% and 43.71% compared to the wild type. In ΔMIG1 strain, the metabolic shifting on the aerobic pathway and a significant increase in pyruvate and glycerol production suggested it as an optimally productive industrial yeast strain. However, further studies are needed to confirm these findings.

The DNA polymerase-encoding gene from a thermoacidophilic archaeon Sulfolobus acidocaldarius.

We have cloned, sequenced and characterized the gene encoding a DNA polymerase from the thermoacidophilic archaeon Sulfolobus acidocaldarius (Sac). The putative transcription promoter and terminator elements, as well as a potential ribosome-binding site (rbs), have been identified in the flanking regions. One large open reading frame (ORF) found in the sequenced portion of the Sac genome encodes a protein of 875 amino acids (aa). All conserved motifs characteristic of family B of DNA polymerases have been found in the deduced primary structure of this enzyme. The Sac DNA polymerase also contains sequence motifs that form a proofreading exonuclease domain.