Hap1 and Rox1 are transcriptional regulators that bind regulatory sites in the promoters of oxygen-regulated genes in Saccharomyces cerevisiae. Hap1 is a heme-responsive activator of genes induced in aerobic conditions and Rox1 is a repressor of hypoxic genes in aerobic conditions. We have studied transcriptional regulation of a pool of 203 open reading frames (ORFs) from chromosomes IV, VII, and XIV in wild-type, hap1, and rox1 mutant genetic backgrounds in an attempt to extend the family of oxygen and heme regulated genes. Only three ORFs are significantly repressed by Rox1 but they cannot be considered as typical hypoxic genes because they are not overexpressed during hypoxia.
In the present study we investigate the microbial community inhabiting As Burgas geothermal spring, located in Ourense (Galicia, Spain). The approximately 23 Gbp of Illumina sequences generated for each replicate revealed a complex microbial community dominated by Bacteria in which Proteobacteria and Aquificae were the two prevalent phyla. An association between the two most prevalent genera, Thermus and Hydrogenobacter, was suggested by the relationship of their metabolism. The high relative abundance of sequences involved in the Calvin–Benson cycle and the reductive TCA cycle unveils the dominance of an autotrophic population. Important pathways from the nitrogen and sulfur cycle are potentially taking place in As Burgas hot spring. In the assembled reads, two complete ORFs matching GH2 beta-galactosidases were found. To assess their functional characterization, the two ORFs were cloned and overexpressed in E. coli. The pTsbg enzyme had activity towards o-Nitrophenyl-β-d-galactopyranoside (ONPG) and p-Nitrophenyl-β-d-fucopyranoside, with high thermal stability and showing maximal activity at 85 °C and pH 6, nevertheless the enzyme failed to hydrolyze lactose. The other enzyme, Tsbg, was unable to hydrolyze even ONPG or lactose. This finding highlights the challenge of finding novel active enzymes based only on their sequence.
Here, we present the draft genome sequence of Kluyveromyces marxianus CCT 7735 (UFV-3), including the eight chromosomes and the mitochondrial genomic sequences.
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