Coexistence of different pathways in the metabolism of n-propylbenzene by Pseudomonas sp

Pseudomonas desmolytica S449B1 and Pseudomonas convexa S107B1 grown on n-propylbenzene oxidized n-propylbenzene to beta-phenylpropionic acid and benzoic acid by initial oxidation of the n-propyl side chain and the following beta-oxidation, respectively. The same strains also oxidized n-propylbenzene to 3-n-propylcatechol by initial oxidation of positions 2 and 3 of the aromatic nucleus. A ring fission product, 2-hydroxy-6-oxononanoic acid, was also isolated from the culture broth. Together with the results of oxygen uptake experiments, the data obtained suggested not only the existence of a reductive step to form 2-hydroxy-6-oxononanoic acid, but also the coexistence of two different pathways in the metabolism of n-propylbenzene by the strains used.     

Improvement of culture conditions and evidence for nuclear transformation by homologous recombination in a red alga, Cyanidioschyzon merolae 10D

Although the nuclear genome sequence of Cyanidioschyzon merolae 10D, a unicellular red alga, was recently determined, DNA transformation technology that is important as a model plant system has never been available thus far. In this study, improved culture conditions resulted in a faster growth rate of C. merolae in liquid medium (doubling time = 9.2 h), and colony formation on gellan gum plates. Using these conditions, spontaneous mutants (5-fluoroortic acid resistant) deficient in the UMP synthase gene were isolated. The lesions were then restored by introducing the wild-type UMP synthase gene into the cells suggesting DNA transformation by homologous recombination.     

Partial Characterization of Cell-bound Lipase of Candida paralipolytica

In accordance with the regulation by aspartate of phosphoenolpyrubate (PEP*) carboxylase, glutamate formation in Brevibacterium flavum, a glutamate-producing bacterium, was inhibited by the addition of aspartate. Furthermore, an increase in aspartate formation caused by a mutational decrease in citrate synthase specific activity was accompanied by a decrease in the total amount of glutamate and aspartate formed. However, a mutational decrease in glutamate dehydrogenase activity caused a decrease in the total amount without increasing the asparate formation but with accumulation of 2-oxoglutarate, suggesting that the feedback inhibition by the aspartate of PEP carboxylase was enhanced by 2-oxoglutarate. In fact, partially purified PEP carboxylase from this organism was found to be synergistically inhibited by aspartate and 2-oxoglutarate, citrate, cis-aconitase, or isocitrate. Among them, the effects of tricarboxylic acids were attributed to their non-specific chelating action with Mn²⁺, an activator of the enzyme. The synergistic action of 2-oxoglutarate was accompanied by a decrease in Hill coefficient for the aspartate of the enzyme.     

Production of Pyoluteorin and Its Derivatives from n-Paraffin by Pseudomonas aeruginosa S10B2

In investigations of biological active substances in metabolites of n-paraffin-utilizing microorganisms, Pseudomonas aeruginosa (Schroeter) S10B2 isolated from soil was found to produce pyoluteorin and its derivatives. One derivative was identified as 3′-nitropyoIuteorin, a new metabolite of microorganisms. Some of these products were found to have antimicrobial activity in vitro and in vivo. In addition, the herbicidal activity of these products was discovered.     

Screening of n-Alkylbenzenes Assimilating Yeasts and Identification of Oxidation Products from n-Alkylbenzenes

As a result of screening of n-alkylbenzenes assimilating yeasts, it was shown that the yeasts which grew well on n-alkane (C₁₅) showed also good growth on n-alkylbenzenes (from C₇ to C₁₉ of side chain). Among four Candida strains selected, C. tropicalis S131Y1 produced 4-(o-hydroxyphenyl)-butyric acid, o-hydroxy phenylacetic acid and phenylacetic acid from n-alkylbenzenes with even-carbon side chain and cinnamic acid from n-alkylbenzenes with odd-carbon side chain.

On the other hand, another three strains produced only phenylacetic acid from n-alkyl-benzenes with even-carbon side chain. In addition, as for the products from n-alkylbenzenes with odd-carbon side chain, two of three strains, C. parapsilosis IFO-1068 and C hydrocarbofumarica Et 15-2 produced benzoic acid.

From these oxidation products and oxygen uptake experiment, a new metabolic pathway of K-alkylbenzenes was assumed.     

HTLV-1 Tax-mediated TAK1 activation involves TAB2 adapter protein

Human T cell leukemia virus type 1 (HTLV-1) Tax is an oncoprotein that plays a crucial role in the proliferation and transformation of HTLV-1-infected T lymphocytes. It has recently been reported that Tax activates a MAPKKK family, TAK1. However, the molecular mechanism of Tax-mediated TAK1 activation is not well understood. In this report, we investigated the role of TAK1-binding protein 2 (TAB2) in Tax-mediated TAK1 activation. We found that TAB2 physically interacts with Tax and augments Tax-induced NF-κB activity. Tax and TAB2 cooperatively activate TAK1 when they are coexpressed. Furthermore, TAK1 activation by Tax requires TAB2 binding as well as ubiquitination of Tax. We also found that the overexpression of TRAF2, 5, or 6 strongly induces Tax ubiquitination. These results suggest that TAB2 may be critically involved in Tax-mediated activation of TAK1 and that NF-κB-activating TRAF family proteins are potential cellular E3 ubiquitin ligases toward Tax.     

Extracellular Polysaccharide Formed by Pseudomonas hydrogenovora in Autotrophic Culture and Its Physiological Activities

Gram negative hydrogen bacterium Pseudomonas hydrogenovora was found to excrete an anthrone-H₂SO₄ positive viscous polysaccharide. About 12 g/liter of the polysaccharide was produced autotrophically on gaseous hydrogen at the stationary phase of growth. Biosynthesis of the polysaccharide occurred under nitrogen-deficient condition. Its elementary composition was C: 39.29%, H: 6.23%, O: 49.67%, N: 0.21% and ash 4.6%. The polysaccharide contained galactose, glucose, mannose and rhamnose as its main components. The polysaccharide had anti-tobacco mosaic virus and anti-tumor activities.     

Microbial transformation of α-pinene

Summary A bacterium capable of utilizing -pinene as a sole carbon and energy source was isolated from soil. This strain, named strain S201-1, which was identified as Pseudomonas maltophilia on the basis of its taxonomical properties, accumulated limonene, borneol, camphor, perillic acid, and 2-(4-methyl-3-cyclohexenylidene) propionic acid from -pinene in the culture broth. It was demonstrated that -pinene, -pinene, borneol, camphor, and a number of p-menthane derivatives were oxidized by this strain. Relations between the protonation of -pinene and the formation of the products by the microbe are discussed.     

Human serum albumin as an antioxidant in the oxidation of (-)-epigallocatechin gallate: participation of reversible covalent binding for interaction and stabilization

Human serum albumin (HSA) contributes to the stabilization of (-)-epigallocatechin gallate (EGCg) in serum. We characterize in the present study the mechanisms for preventing EGCg oxidation by HSA. EGCg was stable in human serum or buffers with HSA, but (-)-epigallocatechin (EGC) was unstable. We show by comparing EGCg and EGC in a neutral buffer that EGCg had a higher binding affinity than EGC. This indicates that the galloyl moiety participated in the interaction of EGCg with HSA and that this interaction was of critical importance in preventing EGCg oxidation. The binding affinity of EGCg for HSA and protein carbonyl formation in HSA were enhanced in an alkaline buffer. These results suggest the reversible covalent modification of EGCg via Schiff-base formation, and that the immobilization of EGCg to HSA, through the formation of a stable complex, prevented the polymerization and decomposition of EGCg in human serum.