Showing papers on "Pseudomonas putida published in 1969"

Phenol and benzoate metabolism by Pseudomonas putida: regulation of tangential pathways.

Abstract: Catechol occurs as an intermediate in the metabolism of both benzoate and phenol by strains of Pseudomonas putida. During growth at the expense of benzoate, catechol is cleaved ortho (1,2-oxygenase) and metabolized via the β-ketoadipate pathway; during growth at the expense of phenol or cresols, the catechol or substituted catechols formed are metabolized by a separate pathway following meta (2,3-oxygenase) cleavage of the aromatic ring of catechol. It is possible to explain the mutually exclusive occurrence of the meta and ortho pathway enzymes in phenol- and benzoate-grown cells of P. putida on the basis of differences in the mode of regulation of these two pathways. By use of both nonmetabolizable inducers and blocked mutants, gratuitous synthesis of some of the meta pathway enzymes was obtained. All four enzymes of the meta pathway are induced by the primary substrate, cresol or phenol, or its analogue. Three enzymes of the ortho pathway that catalyze the conversion of catechol to β-ketoadipate enol-lactone are induced by cis,cis-muconate, produced from catechol by 1,2-oxygenase-mediated cleavage. Observations on the differences in specificity of induction and function of the two pathways suggest that they are not really either tangential or redundant. The meta pathway serves as a general mechanism for catabolism of various alkyl derivatives of catechol derived from substituted phenolic compounds. The ortho pathway is more specific and serves primarily in the catabolism of precursors of catechol and catechol itself.

Inducible Degradation of Hydroxyproline in Pseudomonas putida: Pathway Regulation and Hydroxyproline Uptake

Abstract: Studies in Pseudomonas putida of the inducible degradation of hydroxyproline to α-ketoglutarate have indicated that either of the two epimers, hydroxy-l-proline or allohydroxy-d-proline, acts as an inducer of all the pathway enzymes. In a mutant lacking the first enzyme of the sequence, hydroxyproline-2-epimerase, which interconverts these two hydroxyproline epimers, either epimer is still equally active as an inducer of the remaining three enzymes, suggesting that each epimer has intrinsic inducer activity. The second and third enzymes of the sequence were induced coordinately. The induction process appeared to be insensitive to catabolite repression under a number of experimental conditions. The induced enzymes were stable even under conditions of nitrogen starvation and other conditions designed to increase protein turnover. In addition to inducing the degradative enzymes, the two hydroxyproline epimers were also found to induce an uptake system that concentrates hydroxyproline intracellularly. Either amino acid induced the uptake system for its epimer as well as for itself.

Regulation of the meta Cleavage Pathway for Benzoate Oxidation by Pseudomonas putida

Abstract: Catechol or 2-hydroxymuconic semialdehyde cannot participate as functional inducers of the meta pathway for benzoate metabolism in Pseudomonas putida. Induction of the first two enzymes of the pathway must be mediated by benzoate, or its analogues, as primary substrate.

DEFECTIVE PHAGE AND CHROMOSOME MOBILIZATION IN Pseudomonas putida

Abstract: The transfer of transducing phage DNA in association with the mandelate genetic region of Pseudomonas putida strain PRS1 (termed pfdm) has been achieved by growing together mandelate-positive PpG2 cells harboring pfdm as an extrachromosomal element and mandelate-deleted PpG1 strains. This transfer is analogous to sexual conjugation in the enterobacteria. The transfer of pfdm elements is always associated with chromosome mobilization and some rare recombinants acquire genetic donor ability. We have therefore concluded that the pfdm elements are responsible for initiation of chromosome mobilization in a manner not yet fully understood.

α-Hydroxyglutarate Oxidoreductase of Pseudomonas putida

Abstract: Oxidation of d-α-hydroxyglutarate to α-ketoglutarate is catalyzed by d-α-hydroxyglutarate oxidoreductase, an inducible membrane-bound enzyme of the electron transport particle [ETP; a comminuted cytoplasmic membrane preparation with enzymic properties and chemical composition resembling beef heart mitochondrial ETP (1)] of Pseudomonas putida P2 (P2-ETP). Treatment of P2-ETP with a nonionic detergent yields a preparation with the sedimentation characteristics of a soluble enzyme, but which retains an intact electron transport chain. Oxygen acts solely as a terminal electron acceptor and may be replaced by ferricyanide, 2,6-dichlorophenol indophenol, or mammalian cytochrome c . The oxidoreductase is specific for the d-isomer ( K m = 4.0 × 10 −4 m for dl-α-hydroxyglutarate) and is distinct both from l- and d-malate dehydrogenases. Spectral studies suggest that the carrier sequence is substrate → flavine or nonheme iron → cyt b → [cyt c] → oxygen.