Project description:We assessed changes in gene expression in response to iron availability for the human pathogen Corynebacterium diphtheriae. Expression profiles of wild-type C. diphtheriae strain 1737 grown in semi-defined metal-poor media (mPGT) in iron-limiting (0.5 µM iron chloride supplementation) and iron-replete (10 µM supplementation) conditions were compared; the expression profiles of wild-type C. diphtheriae strain 1737 during growth in iron-replete conditions was also compared against an isogenic ΔdtxR mutant grown in iron-replete conditions. Three biological replicates were prepared by isolating total RNA from mid-logarithmic growth cultures and ten genes (dip0169, dip0415, dip1061, dip1062, dip2330, dip1486, dip0173, dip1252, dip1866, and dip0281) were quantified by real-time PCR to validate the array results. Corynebacterium diphtheriae is the causative agent of the severe respiratory disease, diphtheria. Diphtheria Toxin (DT), encoded by the tox gene, is the potent exotoxin secreted by C. diphtheriae responsible for much of the morbidity and mortality of diphtheria. Expression of the tox gene is regulated by the Diphtheria Toxin Repressor (DtxR) and iron. In addition to the regulation of toxin expression, DtxR functions as a global iron-dependent regulatory factor that mediates iron homeostasis in C. diphtheriae. While numerous genes regulated by DtxR and iron are known, a genome-wide study of both the iron and DtxR regulons is lacking in C. diphtheriae. Here, we report novel iron- and DtxR-regulated genes revealed by a comprehensive transcriptomic analysis. Not all identified genes appear to be repressed by iron and DtxR; some genes were found to be induced by iron in a DtxR-dependent manner, a mechanism of regulation not previously described in C. diphtheriae. Using a prediction algorithm (MEME) and electrophoretic mobility shift assays, we verified DtxR binding to sequences upstream of several newly identified genes. Furthermore, we characterized expression of ferritin (ftn) and catalase (cat), which are both induced by iron, but differentially affected by DtxR. We identified three DtxR binding sites in the ftn promoter, while analysis of the cat promoter establishes a role for DtxR in cat expression and suggests complex regulation by additional regulators. Collectively, these results expand our knowledge on the function of DtxR and the diverse roles of this regulatory protein in controlling gene expression. Overall design: Total RNA harvested from mid-logarithmic cultures of Corynebacterium diphtheriae strain 1737 (wild type and an isogenic dtxR mutant) with low-iron (wild type only) and high-iron (both strains) was assessed for differences. Three separate cultures were used per strain and condition for a total of nine samples.
Project description:To identify genes which are differentially expressed in Corynebacterium glutamicum chassis C1 in comparison to the prophage free strain MB001, we performed DNA microarray analyses of C. glutamicum C1 against MB001. For this purpose RNA was isolated from cells cultivated in CGXII minimal medium with 2% glucose (w v-1) and harvested in the exponential growth phase at an OD600 of 5. Four biological replicates were performed. Overall design: Corynebacterium glutamicum chassis C1 in comparison to the prophage free strain MB001
Project description:Purpose: dissolved oxygen (DO) level is an important factor that could significantly influence microorganisms’ growth, maintenance, metabolism and product yield. The goals of this study are to do comparative analysis on Corynebacterium glutamicum transcriptome in response to the change of dissolved oxygen in bioreactor, find the critical pathways and genes. Overall design: Method: three batches of fermentation were conducted with different DO level separately (50%, 30%, 0%), and sampled on 20h of fermentation, the transcriptome of Corynebacterium glutamicum generated using Illumina hiseq 2000.
Project description:Purpose:dissolved oxygen (DO) level is an important factor that could significantly influence microorganisms’ growth, maintenance, metabolism and product yield.The goals of this study are to comparative analysis on Corynebacterium glutamicum transcriptome in response to expression of eGFP under the change of dissolved oxygen in bioreactor,find the critical pathways and genes. Overall design: Method:three batches of fermentation were conducted with different DO level separately (50%, 30%, 0%),and sampled on 20h of fermentation,the transcriptome of Corynebacterium glutamicum generated using Illumina hiseq 2500.
Project description:(Coryno)mycolate is a α-branched, β-hydroxylated long-chain fatty acid specifically synthesized in bacteria in the suborder Corynebacterineae of the phylum Actinobacteria. It forms an outer membrane and functions as a permeability barrier conferring pathogenic mycobacteria to resistance to antibiotics. Whereas mycolate biosynthetic pathway has been intensively studied, the studies on the transcriptional regulation of genes involved in the pathway are limited. Here, we report that the previously uncharacterized extracytoplasmic function σ factor, σD, is a key regulator of the mycolate synthetic genes in Corynebacterium glutamicum in the suborder. Chromatin immunoprecipitation with microarray analysis detected σD-binding regions in the genome, establishing a consensus promoter sequence for σD recognition. The σD regulon comprises acyl-CoA carboxylase subunits, acyl-AMP ligase, polyketide synthase, and mycolyltransferases, all of which are involved in mycolate synthesis. Actually, deletion or overexpression of sigD encoding σD modified the amount of extractable mycolate. Immediately downstream of sigD, rsdA encoded anti-σD and was under the control of a σD-dependent promoter. Another σD regulon member, L,D-transpeptidase, conferred lysozyme resistance. Thus, σD modifies cell wall composition and enhances mycolate synthesis to provide resistance to environmental stress. Overall design: ChIP-chip analyses using a strain expressing the FLAG-tagged SigD in the background of the wild type at the exporenatial phases. Two independent experiments were performed.
Project description:Mycothiol (AcCys-GlcN-Ins, MSH) is the major thiol-redox buffer in Actinomycetes, including Mycobacterium and Corynebacterium species. Protein S-mycothiolation controls the activities of several redox enzymes that function in detoxification of ROS and methionine sulfoxides, including the thiol peroxidase Tpx, the mycothiol peroxidase Mpx and the methionine sulfoxide reductase MsrA. Here we investigated the level of protein S-mycothiolation in Corynebacterium diphtheriae DSM43989 under oxidative stress as well as its NaOCl stress response.
Project description:Metabolically engineered Corynebacterium glutamicum strains were constructed for the enhanced production of L-arginine, and their gene expression profiles were investigated Gene expression profiles of two C. glutamicum strains AR2 and AR6 were examined for the 3043 genes twice.
Project description:The physiological role of ubiquitous rhomboid proteases, membrane-integral proteins that cleave their substrates inside the lipid bilayer, is ill-defined in prokaryotes. The two rhomboid genes cg0049 and cg2767 of Corynebacterium glutamicum were deletedand consequences investigated in respect to growth phenotype, stress resistance, transcriptome, proteome and lipidome composition.