Publications by authors named "Jan van Ooyen"

Corynebacterium glutamicum is the major host for the industrial production of amino acids and has become one of the best studied model organisms in microbial biotechnology. Rational strain construction has led to an improvement of producer strains and to a variety of novel producer strains with a broad substrate and product spectrum. A key factor for the success of these approaches is detailed knowledge of transcriptional regulation in C.

View Article and Find Full Text PDF

The pentanol isomers 2-methyl-1-butanol and 3-methyl-1-butanol represent commercially interesting alcohols due to their potential application as biofuels. For a sustainable microbial production of these compounds, Corynebacterium glutamicum was engineered for producing 2-methyl-1-butanol and 3-methyl-1-butanol via the Ehrlich pathway from 2-keto-3-methylvalerate and 2-ketoisocaproate, respectively. In addition to an already available 2-ketoisocaproate producer, a 2-keto-3-methylvalerate accumulating C.

View Article and Find Full Text PDF

Peptidyl-prolyl cis/trans isomerases (PPIases) catalyze the rate-limiting protein folding step at peptidyl bonds preceding proline residues and were found to be involved in several biological processes, including gene expression, signal transduction, and protein secretion. Representative enzymes were found in almost all sequenced genomes, including Corynebacterium glutamicum, a facultative anaerobic Gram-positive and industrial workhorse for the production of amino acids. In C.

View Article and Find Full Text PDF

2-Ketoisocaproate (KIC), the last intermediate in l-leucine biosynthesis, has various medical and industrial applications. After deletion of the ilvE gene for transaminase B in l-leucine production strains of Corynebacterium glutamicum, KIC became the major product, however, the strains were auxotrophic for l-isoleucine. To avoid auxotrophy, reduction of IlvE activity by exchanging the ATG start codon of ilvE by GTG was tested instead of an ilvE deletion.

View Article and Find Full Text PDF

Corynebacterium glutamicum, like Mycobacterium tuberculosis, is a member of the Corynebacteriales, which have linear fatty acids and as branched fatty acids the mycolic acids. We identified accD1 and fasA as key genes of fatty acid synthesis, encoding the β-subunit of the acetyl-CoA carboxylase and a type-I fatty acid synthase, respectively, and observed their repression during growth on minimal medium with acetate. We also identified the transcriptional regulator FasR and its binding sites in the 5′ upstream regions of accD1 and fasA.

View Article and Find Full Text PDF

L-Isoleucine is an essential amino acid, which is required as a pharma product and feed additive. Its synthesis shares initial steps with that of L-lysine and L-threonine, and four enzymes of L-isoleucine synthesis have an enlarged substrate specificity involved also in L-valine and L-leucine synthesis. As a consequence, constructing a strain specifically overproducing L-isoleucine without byproduct formation is a challenge.

View Article and Find Full Text PDF

Using metabolic engineering, an efficient L-leucine production strain of Corynebacterium glutamicum was developed. In the wild type of C. glutamicum, the leuA-encoded 2-isopropylmalate synthase (IPMS) is inhibited by low L-leucine concentrations with a K(i) of 0.

View Article and Find Full Text PDF

In a former study we showed that Corynebacterium glutamicum grows much faster in defined CGXII glucose medium when growth was initiated in highly diluted environments [Grünberger et al. (2013b) Biotechnol Bioeng]. Here we studied the batch growth of C.

View Article and Find Full Text PDF

Fast growth of industrial microorganisms, such as Corynebacterium glutamicum, is a direct amplifier for the productivity of any growth coupled or decoupled production process. Recently, it has been shown that C. glutamicum when grown in a novel picoliter bioreactor (PLBR) exhibits a 50% higher growth rate compared to a 1 L batch cultivation [Grünberger et al.

View Article and Find Full Text PDF

We here developed a series of Corynebacterium glutamicum strains with gradual decreased specific citrate synthase (CS) activity and quantified in a multifaceted approach the consequences of residual activity on the transcriptome, metabolome, and fluxome level as well as on L-lysine formation and growth. We achieved an intended gradual L-lysine yield increase and recognized and overcame further new limitations in the L-lysine biosynthesis pathway to result in a strain with the highest yield reported so far when assayed under comparable conditions. As a non-intended outcome, a detailed flux analysis revealed an almost constant flux through CS at 10% remaining CS activity, whereas the metabolome data revealed an increase in the oxaloacetate and acetyl-CoA concentrations.

View Article and Find Full Text PDF

The addition of fatty acids to either Escherichia coli or Bacillus subtilis elicits an elaborate cellular response of the lipid metabolism. We found that in Corynebacterium glutamicum the expression of accD1 encoding the β-subunit of the essential acetyl-CoA carboxylase is repressed in acetate-grown cells without the addition of fatty acids. The TetR-type transcriptional regulator NCgl2404, termed FasR, was identified and deleted.

View Article and Find Full Text PDF

Oxoglutarate dehydrogenase (ODH) and pyruvate dehydrogenase (PDH) complexes catalyze key reactions in central metabolism, and in Corynebacterium glutamicum there is indication of an unusual supercomplex consisting of AceE (E1), AceF (E2), and Lpd (E3) together with OdhA. OdhA is a fusion protein of additional E1 and E2 domains, and odhA orthologs are present in all Corynebacterineae, including, for instance, Mycobacterium tuberculosis. Here we show that deletion of any of the individual domains of OdhA in C.

View Article and Find Full Text PDF

Citrate synthase (CS) is located at a major branch point in the metabolism and is required for both tricarboxylic acid and glyoxylic acid cycle activity. Here we show that the CS gene gltA of Corynebacterium glutamicum is monocistronic, but that two transcripts are formed with their transcript initiation sites located 121 bp and 357 bp upstream of the translational start codon, respectively. Northern blot analyses revealed that during growth on acetate the short transcript prevails, whereas during growth on glucose the long transcript is dominant.

View Article and Find Full Text PDF

Two unrelated protein families catalyse the oxidative decarboxylation of 2-oxoacids, i.e. the 2-oxoacid dehydrogenase complexes (OADHCs) and the 2-oxoacid ferredoxin oxidoreductases (OAFORs).

View Article and Find Full Text PDF