Many genes are regulated as an innate part of the eukaryotic cell cycle, and a complex transcriptional network helps enable the cyclic behavior of dividing cells. This transcriptional network has been studied in Saccharomyces cerevisiae (budding yeast) and elsewhere. To provide more perspective on these regulatory mechanisms, we have used microarrays to measure gene expression through the cell cycle of Schizosaccharomyces pombe (fission yeast). The 750 genes with the most significant oscillation ...[more]
Project description:The Streptomyces coelicolor two genes operon SCO5784-SCO5785 encodes a two-component system which functions in a similar manner to that of the Bacillus subtilis DegS-DegU system. Propagation of the regulatory gene in high copy number results in the overproduction of several extracellular enzymes, among them the major extracellular protease, as well as in a higher level of synthesis of the antibiotic actinorhodin. This two-component system seems to control various processes characterised by the transition from primary to secondary metabolism in S. coelicolor, as determined by proteomic and transcriptomic analices. The presence of the regulatory gene in high copy number in S. coelicolor additionally seems to elicit a stringent response in the bacterial cell. Therefore, we propose renaming S. coelicolor genes SCO5784 and SCO5785 as degS and degU, respectively. All microarray analyses were performed with RNA samples obtained from three independent cultures grown under identical conditions. Hybridisation assays were carried out with cDNA obtained from RNA extracted at the late exponential phase of growth (24h). The transcriptional profile of wild type (S. coelicolor M145) cells carrying the multicopy plasmid pIJ487 was compared with that of the same strain carrying the degU gene cloned in the same plasmid under the control of its own promoter (S. coelicolor M28). And the transcriptional profile of wild type (S, coelicolor M145) cells was compared to that of the DegU deficient strain (S. coelicolor I32).
Project description:The genomic and proteomic analyses of Streptomyces lividans strains deficient in the major signal peptidase SipY or in the translocase complex protein SecG resulted in a set of genes being equally regulated. These genes are apparently responsible for the common deficiencies in extracellular protein production and sporulation shared by both mutant strains, constituting a cellular response to the stress caused by the potential malfunction of the translocase complex, which we have named “extracellular protein translocation stress (EPTS)”. All microarray analyses were performed with RNA samples obtained from three independent cultures grown under identical conditions. The cDNA obtained from each RNA preparation of the SipY-deficient strain or the SecG-deficient strain were hybridised with the cDNA obtained from the equivalent RNA preparation of the wild type strain (S. lividans TK21).
Project description:The Streptomyces lividans lsp gene encodes a type II signal peptidase (Lsp) that cleaves the type II leader peptides of lipoproteins. Transcriptional profiling of the bacterium depleted of the lsp gene mainly resulted in deactivation of the sigma U regulon, as well as in downregulation of genes involved in the biogenesis and function of ribosomes and genes encoding some major secretory proteins as determined by hybridisation of commercially available S. lividans genome-wide microarrays. Almost 50% of the dowregulated genes have been described as forming part of the stringent response in streptomycetes. The gene encoding the S. lividans extracellular foldase, the lipoprotein FkpA, is equally downregulated. Therefore, the deletion of lsp from the S. livdans genome temporarily triggers a cellular stress where the stringent response is, at least, partially induced. All microarray analyses were performed with RNA samples obtained from three independent cultures grown under identical conditions. The cDNA obtained from each RNA preparation of the Lsp-deficient strain was hybridised with the cDNA obtained from the equivalent RNA preparation of the wild type strain (S. lividans TK21).
Project description:Caldicellulosiruptor saccharolyticus is an extremely thermophilic, Gram-positive anaerobe, which ferments cellulose-, hemicellulose- and pectin-containing biomass to acetate, CO2 and hydrogen. Its broad substrate range, high hydrogen-producing capacity, and ability to co-utilize glucose and xylose, make this bacterium an attractive candidate for microbial bioenergy production. Glycolytic pathways and an ABC-type sugar transporter were significantly up-regulated during growth on glucose and xylose, indicating that C. saccharolyticus co-ferments these sugars unimpeded by glucose-based catabolite repression. The capacity to simultaneously process and utilize a range of carbohydrates associated with biomass feedstocks represents a highly desirable feature of a lignocellulose-utilizing, biofuel-producing bacterium. Keywords: substrate response C. saccharolyticus was subcultured (overnight) 3 times on the substrate of interest in modified DSMZ 640 medium before inoculating a pH-controlled (pH = 7) 1-liter fermentor containing 4 gram substrate per liter. Cells were grown at 70 °C until mid-logarithmic phase (~OD660 = 0.3-0.4) and harvested by centrifugation and rapid cooling to 4 °C and stored at -80 °C. To elucidate the central carbon metabolic pathways and their regulation, transcriptome analysis was performed after growth on glucose, xylose and a 1:1 mixture of both substrates. L-Rhamnose, which was likely to follow another pathway, was used as a reference substrate.