Project description:Differential gene expression analysis of C. glutamicum ATCC 13032 in presence of 2.5 mM indole compared to control conditions without indole. C. glutamicum ATCC 13032 cells were cultivated in CGXII minimal medium with 40 g per litre glucose in presence of 2.5 mM indole and harvested during exponential phase (o.d.600 4).
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.
Project description:Differential gene expression analysis of C. glutamicum C1 in presence of 3 mM indole-alanine dipeptide compared to control conditions without indole-alanine dipeptide. C. glutamicum C1 cells were cultivated in CGXII minimal medium with 40 g per litre glucose in presence or absence of 3 mM indole-alanine dipeptide and harvested during exponential phase (o.d.600 6).
Project description:In a manner similar to ubiquitin, the prokaryotic ubiquitin-like protein (Pup) has been shown to target proteins for degradation via the proteasome in mycobacteria. However, not all actinobacteria possessing the Pup protein also harbor a proteasome, suggesting fates for pupylated proteins other than degradation via a proteasome or degradation at all. In the present study we set out to study pupylation in the proteasome-lacking non-pathogenic model microorganism and biotechnological workhorse Corynebacterium glutamicum. A defined pup deletion mutant of C. glutamicum ATCC 13032 grew as the control indicating that pupylation seems to be dispensable under the conditions tested. By expression of homologous Pup carrying a poly-histidine tag in C. glutamicum ATCC 13032 we purified the first pupylome of a microorganism lacking a proteasome. Multidimensional Protein Identification Technology (MudPIT) unraveled 54 proteins being pupylated in this organism. Similar to mycobacteria, the majority of pupylated proteins in C. glutamicum can be classified as enzymes of the metabolism or as involved in translation. These results help to elucidate the common target pathways of pupylation in bacteria. Sample 1: For growth in CGXII minimal media, a preculture 1 was grown in 5 ml BHI medium inoculated with a single colony from a fresh BHI agar plate and incubated at 170 rpm for 8 hours. Then 500 M-BM-5l of preculture 1 were used to inoculate preculture 2 in 100 ml shake flasks with 20 ml CGXII minimal medium containing 4 % (w/v) glucose and incubated over night (140 rpm , 30 M-BM-0C ). Subsequent main cultures (50 ml CGXII medium with 4 % glucose) were inoculated with cells from preculture 2 to an OD600 of about 0.4. For DNA microarray analysis, cells were harvested in the exponential growth phase at an OD600 of 4 to 5. After extraction of total RNA 25M-BM-5g of total RNA from C. glutamicum Delta-pup and C. glutamicum WT were compared in two-color microarray analysis. Overall three biological replicates were done. Sample 2-4: For growth in CGXII minimal media, a preculture 1 was grown in 5 ml BHI medium inoculated with a single colony from a fresh BHI agar plate and incubated at 170 rpm for 8 hours. Then 500 M-BM-5l of preculture 1 were used to inoculate preculture 2 in 100 ml shake flasks with 20 ml CGXII minimal medium containing 4 % (w/v) glucose and incubated over night (140 rpm , 30 M-BM-0C ). Subsequent main cultures (50 ml CGXII medium with 4 % glucose) were inoculated with cells from preculture 2 to an OD600 of about 0.4. For growth experiments in complex BHI medium, 20 ml brain heart infusion (BHI) medium (Difco Laboratories, Detroit, USA) were inoculated with a single colony from a fresh BHI agar plate and incubated at 140 rpm as overnight cultures. Subsequent main cultures (50 ml BHI medium) were inoculated with cells from overnight cultures to an optical density at 600 nm (OD600) of about 1. For DNA microarray analysis, cells were harvested in the exponential growth phase at an OD600 of 4 to 5. After extraction of total RNA 25M-BM-5g of total RNA from C. glutamicum Delta-pup and C. glutamicum WT were compared in two-color microarray analysis. Overall three biological replicates were done for each growth medium. Sample 5-6: For growth experiments in complex BHI medium, 20 ml brain heart infusion (BHI) medium (Difco Laboratories, Detroit, USA) were inoculated with a single colony from a fresh BHI agar plate and incubated at 140 rpm as overnight cultures. Subsequent main cultures (50 ml BHI medium) were inoculated with cells from overnight cultures to an optical density at 600 nm (OD600) of about 1. For DNA microarray analysis, cells were harvested in the exponential growth phase at an OD600 of 4 to 5. After extraction of total RNA 25M-BM-5g of total RNA from C. glutamicum Delta-pup and C. glutamicum WT were compared in two-color microarray analysis. Overall three biological replicates were done.
Project description:BackgroundZinc is considered as an essential element for all living organisms, but it can be toxic at large concentrations. Bacteria therefore tightly regulate zinc metabolism. The Cg2502 protein of Corynebacterium glutamicum was a candidate to control zinc metabolism in this species, since it was classified as metalloregulator of the zinc uptake regulator (Zur) subgroup of the ferric uptake regulator (Fur) family of DNA-binding transcription regulators.ResultsThe cg2502 (zur) gene was deleted in the chromosome of C. glutamicum ATCC 13032 by an allelic exchange procedure to generate the zur-deficient mutant C. glutamicum JS2502. Whole-genome DNA microarray hybridizations and real-time RT-PCR assays comparing the gene expression in C. glutamicum JS2502 with that of the wild-type strain detected 18 genes with enhanced expression in the zur mutant. The expression data were combined with results from cross-genome comparisons of shared regulatory sites, revealing the presence of candidate Zur-binding sites in the mapped promoter regions of five transcription units encoding components of potential zinc ABC-type transporters (cg0041-cg0042/cg0043; cg2911-cg2912-cg2913), a putative secreted protein (cg0040), a putative oxidoreductase (cg0795), and a putative P-loop GTPase of the COG0523 protein family (cg0794). Enhanced transcript levels of the respective genes in C. glutamicum JS2502 were verified by real-time RT-PCR, and complementation of the mutant with a wild-type zur gene reversed the effect of differential gene expression. The zinc-dependent expression of the putative cg0042 and cg2911 operons was detected in vivo with a gfp reporter system. Moreover, the zinc-dependent binding of purified Zur protein to double-stranded 40-mer oligonucleotides containing candidate Zur-binding sites was demonstrated in vitro by DNA band shift assays.ConclusionWhole-genome expression profiling and DNA band shift assays demonstrated that Zur directly represses in a zinc-dependent manner the expression of nine genes organized in five transcription units. Accordingly, the Zur (Cg2502) protein is the key transcription regulator for genes involved in zinc homeostasis in C. glutamicum.
Project description:Corynebacterium glutamicum shows a great potential for the production of gamma-aminobutyric acid (GABA) from glucose fermentation via putrescine. GABA, a non-protein amino acid widespread in nature, is a component of pharmaceuticals, foods and the biodegradable plastic polyamide 4. Here, the effect of GABA in the growth of C. glutamicum was evaluated. It was estimated that the presence 1.1 M of GABA in the medium reduces the maximum growth rate of C. glutamicum to half. It was also shown that the presence of GABA in the medium negatively affects the growth of C. glutamicum in ethanol as sole carbon source. Furthermore, a new route for the production of GABA in C. glutamicum was established. GABA production from glucose fermentation via putrescine was achieved by plasmid-based overexpression of putrescine transaminase (PatA) and gamma-aminobutyraldehyde dehydrogenase (PatD) in a putrescine production strain. The resultant strain can produce 5.3 ± 0.1 g L-1 of GABA. GABA production was improved by avoiding the formation of N-acetylputrescine and by reducing the amount of nitrogen in CGXII medium. Deletion of the genes responsible for GABA catabolism and GABA re-uptake led to an increase in the GABA production of 21% achieving a titer 8.0 ± 0.3 g L-1 and an increase in the volumetric productivity of 41% reaching a productivity of 0.31 g L-1 h-1, the highest volumetric productivity achieved so far for GABA production in C. glutamicum from glucose fermentation in flasks fermentations. The results obtained hitherto are very promising and competitive compared to the traditional pathway for the production of GABA.
Project description:The demand for alternative sources of food proteins is increasing due to the limitations and challenges associated with conventional food production. Advances in biotechnology have enabled the production of proteins using microorganisms, thus prompting the exploration of attractive microbial hosts capable of producing functional proteins in high titers. Corynebacterium glutamicum is widely used in industry for the production of amino acids and has many advantages as a host organism for recombinant protein production. However, its performance in this area is limited by low yields of target proteins and high levels of native protein secretion. Despite representing a challenge for heterologous protein production, the C. glutamicum secretome has not been fully characterized. In this study, state-of-the-art mass spectrometry-based proteomics was used to identify and analyze the proteins secreted by C. glutamicum. Both the wild-type strain and a strain that produced and secreted a recombinant β-lactoglobulin protein were analyzed. A total of 427 proteins were identified in the culture supernatants, with 148 predicted to possess a secretion signal peptide. MS-based proteomics on the secretome enabled a comprehensive characterization and quantification (based on abundance) of the secreted proteins through label-free quantification (LFQ). The top 12 most abundant proteins accounted for almost 80% of the secretome. These are uncharacterized proteins of unknown function, resuscitation promoting factors, protein PS1, Porin B, ABC-type transporter protein and hypothetical membrane protein. The data can be leveraged for protein production by, e.g., utilizing the signal peptides of the most abundant proteins to improve secretion of heterologous proteins. In addition, secretory stress can potentially be alleviated by inactivating non-essential secreted proteins. Here we provide targets by identifying the most abundant, secreted proteins of which majority are of unknown function. The data from this study can thus provide valuable insight for researchers looking to improve protein secretion and optimize C. glutamicum as a host for secretory protein production.