Klaus Severin

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The ubiC gene of Escherichia coli encodes chorismate pyruvatelyase, an enzyme that converts chorismate into 4-hydroxybenzoate (4HB) and is not normally present in plants. The ubiC gene was expressed in Nicotiana tabacum L. plants under control of a constitutive plant promoter. The gene product was targeted into the plastid by fusing it to the sequence for(More)
The carbon skeleton of the naphthoquinone pigment shikonin, which is produced in Lithospermum erythrorhizon Sieb. et Zucc. cell-suspension cultures, is partly derived from the isoprenoid biosynthetic pathway. The requirement of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR, EC 1.1.1.34), a key enzyme of the mevalonate route to isoprenoids, for(More)
Symbiosis is an association between different organisms that leads to a reciprocal enhancement of their ability to survive. Similar mutually beneficial relationships can operate at the molecular level in the form of a hypercycle, a collective of two or more self-replicating species interlinked through a cyclic catalytic network. The superposition of(More)
Chorismate pyruvate-lyase from Escherichia coli converts chorismate to 4-hydroxybenzoate. The enzyme was enriched 3000-fold by overexpression and chromatographic purification. It has an apparent Km value for chorismate of 6.1 microM and an isoelectric point of pH 6.45. The enzyme activity did not require metal cofactors. Promoter sequences in the 5'(More)
The production of amino acids and their condensation to polypeptides under plausibly prebiotic conditions have long been known. But despite the central importance of molecular self-replication in the origin of life, the feasibility of peptide self-replication has not been established experimentally. Here we report an example of a self-replicating peptide.(More)
Two cDNA clones (LEPAL-1 and LEPAL-2) encoding phenylalanine ammonia-lyase were isolated from cell suspension cultures of Lithospermum erythrorhizon. Northern kinetic studies showed that LEPAL-1 mRNA contents markedly increased one day after inoculation of the cells into fresh medium, then decreased to the steady-state level. The course of mRNA accumulation(More)
A 33-residue de novo designed peptide ligase is reported which catalyzes the template-directed condensation of suitably activated short peptides with catalytic efficiencies in excess of 10(5) ([k(cat)/K(m)]/k(uncat)). The ligase peptide, derived from natural and designed alpha-helical coiled-coil proteins, presents a surface for substrate assembly via(More)
We have constructed a chimaeric gene consisting of the promoter of the soybean heat shock (hs) gene Gmhsp17,6-L, the coding region of a hygromycin phosphotransferase (hpt) gene, and the termination sequence of the nopaline synthase (nos) gene. This gene fusion was introduced into tobacco by Agrobacterium-mediated gene transfer. Heat-inducible synthesis of(More)
Chorismate pyruvate-lyase activity was detected in extracts of Escherichia coli. 4-Hydroxybenzoate was identified as the product of the enzymatic reaction by chemical derivatization and GC-MS analysis. The ubiC gene, coding for the chorismate pyruvate-lyase, was cloned and sequenced. The molecular weight of the gene product was calculated as 18,776 Da and(More)