Transcriptional activator Cat8 is involved in regulation of xylose alcoholic fermentation in the thermotolerant yeast Ogataea (Hansenula) polymorpha

Additional file 5. List of primers used in this study (restriction sites are underlined)

Functional characterization of zinc cluster transcriptional regulators in Saccharomyces cerevisiae and Candida albicans

Zinc cluster proteins form a major class of fungal-specific transcriptional regulators in Saccharmyces cerevisiae. They are characterized by a well-conserved zinc cluster motif essential for DNA recognition. These regulators are implicated in transcriptional control of genes involved in various cellular processes such in sugar metabolism, biosynthesis of amino acids, gluconeogenesis, ergosterol biosynthesis and pleiotropic drug resistance (PDR)/stress response. A classic example of zinc cluster protein is Gal4, a regulator of galactose catabolism. However, a number of zinc cluster genes encode putative regulators with unknown function. A phenotypic analysis of zinc cluster deletion strains has implicated them in certain pathways. Rds2 was identified as a regulator of PDR in Saccharomyces cerevisiae as it confers resistance to an antifungal agent. A genomewide location approach (ChIP-chip) was employed to assign roles for Rds2. Results showed that Rds2 plays a major role in glucose metabolism. It functions as an activator and a repressor of gluconeogenic genes during the diauxic shift. It also mediates sensitivity to the antifungal drug azoles by regulating the expression of genes in the ergosterol biosynthetic pathway. Its ortholog in the pathogenic yeast Candida albicans, Cwt1, is also involved in glucose metabolism but not in PDR. Functional relationship among known PDR regulators in S. cerevisiae was uncovered in a phenotypic analysis of double deletion of zinc cluster genes. Altogether, this study provides new insight regarding the roles of zinc cluster regulators in transcriptional control of genes involved in multiple physiological process

Regulation of Gluconeogenesis in Saccharomyces cerevisiae Is Mediated by Activator and Repressor Functions of Rds2▿

In Saccharomyces cerevisiae, RDS2 encodes a zinc cluster transcription factor with unknown function. Here, we unravel a key function of Rds2 in gluconeogenesis using chromatin immunoprecipitation-chip technology. While we observed that Rds2 binds to only a few promoters in glucose-containing medium, it binds many additional genes when the medium is shifted to ethanol, a nonfermentable carbon source. Interestingly, many of these genes are involved in gluconeogenesis, the tricarboxylic acid cycle, and the glyoxylate cycle. Importantly, we show that Rds2 has a dual function: it directly activates the expression of gluconeogenic structural genes while it represses the expression of negative regulators of this pathway. We also show that the purified DNA binding domain of Rds2 binds in vitro to carbon source response elements found in the promoters of target genes. Finally, we show that upon a shift to ethanol, Rds2 activation is correlated with its hyperphosphorylation by the Snf1 kinase. In summary, we have characterized Rds2 as a novel major regulator of gluconeogenesis

Trypsin hydrolysed protein fractions as radical scavengers and anti-bacterial agents from ficus deltoidea

Different molecular sizes of protein hydrolysates were prepared from the crude protein extract of Ficus deltoidea using the technique of membrane ultrafiltration after trypsin hydrolysis. Gel electrophoretic images shows the presence of 12, 8, 7 and 7 protein bands for the protein fractions prepared from the molecular weight cut-off of 3, 10, 30 and 100 kDa, respectively. The protein hydrolysates were found to have higher radical scavenging activity than those unhydrolysed fractions at the similar molecular size. They exhibited significant differences in the radical scavenging activities based on one-way analysis of variance, except for the protein hydrolysates of 30 and 100 kDa. The smallest protein hydrolysates, 3 kDa appeared to have the comparable activity (30%) with bovine serum albumin as a positive control in this study. Similarly, the 3 kDa protein hydrolysates achieved the highest inhibitory activity (87.5%) against Pseudomonas aeruginosa at the concentration of 128 µg/mL. The protein hydrolysates were found to be more effective against gram negative bacteria (P. aeruginosa and Escherichia coli) because of lower minimum inhibitory concentration (MIC) and effective inhibitory concentration at 50% (EC50) than gram positive bacterium (Staphylococcus aureus). Trypsin catalysed hydrolysis seemed to improve the anti-bacterial activity of protein hydrolysates in a bacterial strain dependent manner. The MIC could achieve 1–55 µg/mL at different molecular sizes of protein fractions. Mass spectra matching revealed that 26% of 226 identified proteins belonged to the category of plant defensive proteins in stress management and metal handling

Life-span extension by pigmented rice bran in the model yeast Saccharomyces cerevisiae

Benefits of whole grains as dietary supplements and active ingredients in health products have been promoted. Despite being neglected as an agricultural byproduct of polished rice, pigmented rice bran has emerged as a promising source of natural anti-aging compounds. Indeed, the extract of red rice bran Hom Dang cultivar contained rich phenolic acids and flavonoids. It displayed high antioxidant activities in vitro and in vivo assays. Using yeast model, extract and bioactive compounds, quercetin and protocatechuic acid found in the rice bran pericarp, effectively reduced levels of intracellular reactive oxygen species (ROS), restored plasma membrane damages and prolonged life-span of pre-treated wild-yeast cells. Importantly, these molecules modulated life span-extension through a mechanism of ROS reduction that resembles to that operated under the highly conserved Tor1- and Sir2-dependent signaling pathways, with the human homologs TORC1 and SIRT1, respectively. The key longevity factors Sch9 and Rim15 kinases, Msn2/4 regulators and a novel transcription factor Asg1, the antioxidant enzymes superoxide dismutases and glutathione peroxidases played important role in mediating longevity. Yeast clearly provides an instrumental platform for rapid screening of compounds with anti-aging efficacies and advances knowledge in the molecular study of ageing