We have used transpositional mutagenesis of a proline auxotroph (PAO951) to isolate an ornithine utilization (oru) mutant of Pseudomonas aeruginosa (PAO951-4) that was unable to use ornithine efficiently as the sole carbon and nitrogen source. DNA sequence analysis of the inactivated locus confirmed that the transposon had inserted into a locus whose product demonstrated significant primary seq...

BACKGROUND L-ornithine is effective in the treatment of liver diseases and helps strengthen the heart. The commercial applications mean that efficient biotechnological production of L-ornithine has become increasingly necessary. Adaptive evolution strategies have been proven a feasible and efficient technique to achieve improved cellular properties without requiring metabolic or regulatory deta...

We have characterized further the biogenesis in vitro of ornithine transcarbamylase, a homotrimeric mitochondrial matrix enzyme synthesized in the cytoplasm as a larger precursor. When cell-free translation mixtures containing the ornithine transcarbamylase precursor (40 kDa) were chromatographed on Bio-Gel P-200 columns, all of the precursor eluted as aggregates or complexes with molecular wei...

The mould Neurospora crassa is normally able to interconvert proline and ornithine, since either proline or ornithine will satisfy the growth requirement of certain mutant strains (Srb, Fincham & Bonner, 1950). Another mutant requires proline specifically, while numerous other strains, representing at least four different genetic loci, respond to ornithine but not to proline (Srb & Horowitz, 19...

Conditions were found under which the processes of repression and derepression of ornithine transcarbamylase were separated from the process of enzyme synthesis. After 10 min of arginine deprivation followed by the addition of 2 to 200 mug of l-arginine per ml, a number of strains of Escherichia coli exhibited a significant burst of ornithine transcarbamylase synthesis which lasted 3 to 4 min b...

Ornithine is an allosteric activator of carbamoyl phosphate synthetase (CPS) from Escherichia coli. Nine amino acids in the vicinity of the binding sites for ornithine and potassium were mutated to alanine, glutamine, or lysine. The residues E783, T1042, and T1043 were found to be primarily responsible for the binding of ornithine to CPS, while E783 and E892, located within the carbamate domain...

concentrated enzyme extracts with higher specific activities. By performing the assay in the presence of various concentrations of ornithine, we confirmed that AGAT is inhibited by ornithine, as reported previously (7 ). This observation may be of clinical interest in conditions of hyperornithinemia. Decreased brain creatine has been observed in patients affected with gyrate atrophy of the chor...

BACKGROUND In this study, it was aimed to investigate the relationship between diabetes and breast cancer and the detection of enzymes and ornithine levels in polyamine synthesis pathway in diabetes, breast cancer and diabetic breast cancer patients. METHODS Ornithine, arginine decarboxylase, ornithine decarboxylase and agmatinase levels have been measured in serum of all groups. Ornithine le...

Most mitochondrial proteins are encoded in the nucleus and translated in the cytoplasm as larger precursors containing NH2-terminal "leader" peptides, which are strikingly basic in overall amino acid composition. Recent experiments indicate that these leader peptides are both necessary and sufficient to direct post-translational recognition and import of precursors by mitochondria. In this repo...

Intraventricular administration of nanogram quantities of nerve growth factor to adult rats results in a marked increase in the activity of ornithine decarboxylase (L-ornithine carboxy-lyase, EC 4.1.1.17) in the brain. The increase occurs in all major brain regions and the activity is maximal by 7.5 hr after administration. The enzyme response to nerve growth factor increases in magnitude durin...