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Carotenoid biosynthesis in Rhodopseudomonas spheroides. S-adenosylmethionine as the methylating agent in the biosynthesis of spheroidene and spheroidenone.

ABSTRACT: [methyl-(14)C]Methionine and S-adenosyl[methyl-(14)C]methionine were incorporated into the methoxycarotenoids spheroidene and spheroidenone by Rhodopseudomonas spheroides. The incorporation was greatly enhanced in the presence of lysozyme. On degradation of labelled spheroidene by hydriodic acid, the (14)C label was recovered in methyl iodide. Degradation of spheroidenone by reduction and allylic dehydration and demethylation of the reduction product gave a mixture of unlabelled carotenoid hydrocarbons, including 3,4-didehydrolycopene and 3,4-didehydro-7',8'-dihydrolycopene. The label from [methyl-(14)C]methionine and S-adenosyl[methyl-(14)C]methionine was located specifically in the methoxy group of spheroidene and spheroidenone. The biosynthesis of methoxycarotenoids in Rps. spheroides involves methylation of the tertiary hydroxyl groups of intermediates with S-adenosylmethionine.

SUBMITTER: Singh RK

PROVIDER: S-EPMC1165968 | biostudies-other | 1973 Oct

REPOSITORIES: biostudies-other

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Ferrochelatase of Rhodopseudomonas spheroides.

Project description:Extracts of Rhodopseudomonas spheroides contain two ferrochelatases: one is soluble and forms metalloporphyrins from deuteroporphyrin and haematoporphyrin; the other is particulate and forms metalloporphyrins from protoporphyrin, mesoporphyrin, deuteroporphyrin and haematoporphyrin. Neither enzyme incorporates Mg(2+) into porphyrins or Fe(2+) into porphyrin cytochrome c. By using the particulate enzyme, plots of 1/v versus 1/s when one substrate was varied and the other kept constant showed that neither substrate affected the K(m) of the other. The suggested sequential mechanism for the reaction is supported by derivative plots of slopes and intercepts. The K(m) for deuteroporphyrin was 21.3mum and that for Co(2+) was 6.13mum. The enzyme incorporated Co(2+), Fe(2+), Zn(2+), Ni(2+) and Mn(2+); Cd(2+) was not incorporated and was an inhibitor, competitive with respect to Co(2+), non-competitive with respect to deuteroporphyrin. The K(i) for Cd(2+) was 0.73mum. Ferrochelatase was inhibited by protohaem, non-competitively with respect to Co(2+) or with respect to deuteroporphyrin. Inhibition by magnesium protoporphyrin was non-competitive with respect to deuteroporphyrin, uncompetitive with respect to Co(2+). The inhibitory concentrations of the metalloporphyrins are lower than those required for the inhibition of delta-aminolaevulate synthetase by protohaem. Fe(2+) is not incorporated aerobically into porphyrins unless an electron donor, succinate or NADH, is supplied; the low aerobic rate of metalloporphyrin synthesis obtained is insensitive to rotenone and antimycin. The rate of Fe(3+) incorporation increases as anaerobic conditions are achieved.

| S-EPMC1179374 | biostudies-other

Control of porphyrin biosynthesis in Rhodopseudomonas spheroides and Propionibacterium shermanii. A direct 13C nuclear-magnetic-resonance spectroscopy study.

Project description:The facultative anaerobes Rhodopseudomonas spheroides and Propionibacterium shermanii were grown under anaerobic and aerobic conditions. The effect of light was studied with the photosynthetic R. spheroides, and the adaptation of both species to dark anaerobic life was monitored by direct observation of 5-amino[5-13C]laevulinic acid metabolism by using 13C nuclear-magnetic-resonance spectroscopy.

| S-EPMC1162788 | biostudies-other

Control of delta-aminolaevulate synthetase activity in Rhodopseudomonas spheroides.

Project description:1. delta-Aminolaevulate synthetase from Rhodopseudomonas spheroides grown semi-anaerobically undergoes a spontaneous activation during the first hour after the disruption of cells when homogenates are stored at 4 degrees . 2. After cultures of R. spheroides growing semi-anaerobically are oxygenated no activation of delta-aminolaevulate synthetase occurs in cell extracts. Cessation of activation in extracts is almost complete 10min. after oxygenation of cells has begun. 3. A heat-stable fraction of low molecular weight from semi-anaerobic cells reactivates delta-aminolaevulate synthetase in extracts of oxygenated cells and appears to contain a compound responsible for the spontaneous activation. 4. A heat-stable fraction of low molecular weight from oxygenated cells inhibits the spontaneous activation in extracts of semi-anaerobic cells. 5. The effect of oxygen on the rate of bacteriochlorophyll synthesis in R. spheroides may be mediated through alterations in the concentrations of a low-molecular-weight activator and inhibitor of delta-aminolaevulate synthetase.

| S-EPMC1187556 | biostudies-other

Activation of delta-aminolaevulate synthetase in extracts of Rhodopseudomonas spheroides.

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| S-EPMC1178966 | biostudies-other

Glycine decarboxylase in Rhodopseudomonas spheroides and in rat liver mitochondria.

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| S-EPMC1179293 | biostudies-other

Coproporphyrinogenase activities in extracts of Rhodopseudomonas spheroides and Chromatium strain D.

Project description:1. The anaerobic coproporphyrinogenase activity in an extract of Rhodopseudomonas spheroides is inhibited by 1,10-phenanthroline, alphaalpha'-bipyridyl, flavins, 2,4-dinitrophenol and 1,4-naphthaquinone. These compounds have no effect on the aerobic coproporphyrinogenase activity. 2. On removal of small-molecular-weight material from a crude extract, the anaerobic system becomes very unstable; it can be stabilized by adding succinate. Now nicotinamide nucleotides, in addition to Mg(2+), ATP and methionine, are required for protoporphyrin to be formed. 3. A mechanism for the anaerobic reaction is proposed, based on the cofactor requirements and the effect of inhibitors. 4. The enzyme responsible for aerobic activity has been partially purified and some of its properties are reported. 5. A crude extract of Chromatium strain D also exhibits coproporphyrinogenase activity under anaerobic conditions in the presence of S-adenosylmethionine or ATP plus methionine. The requirement for other cofactors is variable.

| S-EPMC1174004 | biostudies-other

Magnesium protoporphyrin chelatase activity in Rhodopseudomonas spheroides. Studies with whole cells.

Project description:1. Whole cells of Rhodopseudomonas spheroides grown under semi-anaerobic conditions in the light incorporated magnesium into exogenous protoporphyrin when incubated with EDTA or the related chelators EGTA, N-(2-hydroxyethyl)-ethylenediamine-NN'N'- triacetate and trans-1,2-diaminocyclohexanetetra-acetate. 2. The reaction was demonstrated under anaerobic conditions in the light or at low oxygen partial pressure in the dark. Partial pressures of oxygen greater than 15% inhibited the reaction. 3. Cells grown under pure oxygen were completely inactive, but on adaptation to growth under low oxygen partial pressure (O(2)+N(2), 5:95) the development of activity paralleled the synthesis of bacteriochlorophyll. 4. The reaction with normal cells did not require protein synthesis, but cells that had lost their activity by being illuminated in Mg(2+)-deficient medium did not recover it in the absence of protein synthesis. 5. The product of the reaction was magnesium protoporphyrin monomethyl ester. 6. Evidence is presented that insertion of magnesium is obligatorily coupled with methylation and it is concluded that the reaction is dependent on a multienzyme complex.

| S-EPMC1178563 | biostudies-other

Purification and properties of crystalline 3-hydroxybutyrate dehydrogenase from Rhodopseudomonas spheroides.

Project description:1. The purification and crystallization of 3-hydroxybutyrate dehydrogenase from extracts of Rhodopseudomonas spheroides is described. 2. The molecular weight was calculated to be 85000 by sedimentation equilibrium. 3. Although the enzyme is stable at 0-4 degrees , dilute solutions are rapidly inactivated at 37 degrees ; NADH(2) or Ca(2+) ions prevent this inactivation. 4. The enzyme is extremely sensitive to mercurials, but can be protected by NADH(2) or Ca(2+) ions. 5. From studies on p-hydroxymercuribenzoate binding it is estimated that the enzyme contains 5-6 moles of rapidly reacting thiol groups/mole. 6. d-Lactate and dl-2-hydroxybutyrate are competitive inhibitors of d-3-hydroxybutyrate oxidation. 7. The properties of the crystalline enzyme are compared with those of 3-hydroxybutyrate dehydrogenase preparations from other sources.

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Expression Analysis of Carotenoid Biosynthesis Pathway Genes in Tomato

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2011-01-04 | E-MEXP-2934 | biostudies-arrayexpress

Polypyrroles formed from porphobilinogen and amines by uroporphyrinogen synthetase of Rhodopseudomonas spheroides.

Project description:1. Uroporphyrinogen I synthetase of Rhodopseudomonas spheroides was purified more than 200-fold from the soluble protein of broken bacterial cells. The enzyme had molecular weight 36000, an isoelectric point of 4.46 and migrated as a single active protein band on disc-gel electrophoresis at pH7.5 and 8.9. 2. The enzyme consumed porphobilinogen and formed uroporphyrinogen at pH8.2 without the accumulation of intermediates. In the presence of hydroxylamine, ammonia or methoxyamine the production of porphyrinogen was inhibited and the enzyme formed open-chain polypyrroles instead. 3. These polypyrroles behaved like uroporphyrinogen on Sephadex G-25; they were colourless and had unsubstituted alpha-pyrrolic positions. The inhibitory amines were incorporated into the molecules. 4. The polypyrroles formed porphyrins non-enzymically and the cyclization reaction was accompanied by the release of the inhibitory amine. Exchange of the amino function of the original porphobilinogen in the polypyrrole was complete with hydroxylamine and almost complete with methoxyamine, both ammonia and methoxyamine being present in the polypyrrolic material. 5. The behaviour, properties and composition of the radioactive hydroxylamine derivative were consistent with a tetrapyrrolic structure, probably a pyrrylmethane, that was not cyclized, rather than with di-, tri- or penta-pyrrolic structures. No monopyrrolic or dipyrrolic Ehrlich-positive material was released on cyclization. The ammonia and methoxyamine derivatives had properties similar to the hydroxylamine derivative. 6. Another modified pyrrole was detected only in experiments with hydroxylamine. It differed from both porphobilinogen and known dipyrroles and appeared to be a monopyrrole. 7. The participation of positively charged reaction centres in the enzymic mechanism, particularly in the cyclization step, is discussed.

| S-EPMC1177725 | biostudies-other

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