Biosynthesis of Protoheme and Heme <i>a</i> Precursors Solely from Glutamate in the Unicellular Red Alga <i>Cyanidium caldarium</i>

Weinstein, Jon D.; Beale, Samuel I.

doi:10.1104/pp.74.1.146

Cited by 44 publications

(23 citation statements)

References 16 publications

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“…Dithionite-reduced pyridine hemochrome spectra of the protoheme and heme a peaks are shown in Figure 2. The major absorption bands for protoheme occurred at 419 and 557 nm, and for heme a at 429 and 588 nm, which correspond to the values previously reported for authentic protoheme (26) and heme a (7 between 8 and 10 min, which contained most of the protoheme, although some radioactivity was measured in other fractions (Figs. 3, 4).…”

Section: Materials and Methods Plant Material Seeds Of Zea Mays CV 3supporting

confidence: 51%

“…Noncovalently bound hemes were next extracted by resus- Protoheme and heme a were further purified and separated from each other by reverse-phase HPLC as previously described (25,26,28 Extraction of Total and Nonsaponifiable Lipids. Each initial acetone extract of the tissue section homogenates (100 ml) was filtered through glass fiber filter paper.…”

Section: Materials and Methods Plant Material Seeds Of Zea Mays CV 3mentioning

confidence: 99%

“…The phytoflagellate Euglena gracilis has both pathways: plastid tetrapyrroles are made from glutamate, while mitochondrial hemes, including heme a, are made from glycine (25). In contrast, the unicellular red alga Cyanidium caldarium forms all cellular tetrapyrroles, including mitochondrial heme a, from glutamate (26). It is not possible to extrapolate from these 'Supported by National Science Foundation Grants DMB-8213948 and DMB-85 18580.…”

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confidence: 99%

“…Animals and some bacteria, including photosynthetic bacteria, form ALA exclusively via ALA synthase (1 1,14,19). On the other hand, plants and algae form Chl and plastid hemes from ALA made via the five-carbon route (1,6,18,21,25,26). The phytoflagellate Euglena gracilis has both pathways: plastid tetrapyrroles are made from glutamate, while mitochondrial hemes, including heme a, are made from glycine (25).…”

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confidence: 99%

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Biosynthesis of Protoheme and Heme a from Glutamate in Maize

Schneegurt

Beale²

1986

Plant Physiol.

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The heme and chlorophyll precursor Saminolevulinic acid (ALA) can be formed by two biosynthetic routes: from the intact carbon skeleton of glutamate via a five-carbon pathway, which occurs in chloroplasts and bluegreen algae, and by ALA synthase-catalyzed condensation of succinyl-CoA and glycine, which occurs in bacteria and animal mitochondria. The biosynthetic route of plant mitochondrial heme a was determined by incubating terminal epicotyl sections of 8-day-old etiolated Zea mays seedlings in the dark with L-1-14"Cglutamate (which can be incorporated into ALA only via the five-carbon route) or 2-1[4Cjglycine (which would be incorporated via ALA synthase). Label incorporation was measured in highly purified protoheme and heme a. In 12-hour incubations, label uptake was greater than 70%. Total cellular protoheme was labeled 29.7 times more effectively by glutamate than glycine. Heme a was labeled 4.1 times more effectively by glutamate than by glycine. To assess the relative ability of the two amino acids to contribute label to the farnesyl moiety of heme a, label incorporation into total cellular nonsaponifiable lipids was measured. Glycine labeled this fraction 11.3 times more effectively than glutamate. Thus, a contribution by glycine to the farnesyl moiety may account for the small amount of label appearing in heme a. Our results indicate that in etiolated maize, noncovalently bound hemes, including mitochondrial heme a, are made mostly, and possibly entirely, from ALA synthesized via the five-carbon pathway. There is little or no contribution from ALA formed via ALA synthase, and no evidence was found for the operation of this enzyme in maize.

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Section: Materials and Methods Plant Material Seeds Of Zea Mays CV 3supporting

confidence: 51%

Section: Materials and Methods Plant Material Seeds Of Zea Mays CV 3mentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Biosynthesis of Protoheme and Heme a from Glutamate in Maize

Schneegurt

Beale²

1986

Plant Physiol.

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“…In this HPLC system, biliverdin and the two product pigments eluted at 14 min, 18 min, and 25 min, respectively. The nonradioactive peaks at 36 and 47 min were due to protoheme and heme a, respectively (23), which were derived from hemoproteins present in the crude cell extract.…”

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confidence: 99%

Enzymic Transformation of Biliverdin to Phycocyanobilin by Extracts of the Unicellular Red Alga Cyanidium caldarium

Beale¹,

Cornejo²

1984

Plant Physiol.

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Cell-free extracts of the unicellular red alga Cyanidium caldarium catalyze the transformation of biliverdin to a product indistinguishable from phycocyanobilin, the free bilin derived from phycocyanin by methanolysis. Crude cell-free extract requires biliverdin as the only substrate, but after removal of low molecular weight components by gel filtration, the reaction shows an additional requirement for a reduced pyridine nucleotide. Boiled extract is enzymically inactive, activity is not sedimented by high-speed centrifugation, and mesobiliverdin cannot serve as a substrate.Incubation of cell extracts with biliverdin yields two products with very similar spectrophotometric properties in acidic methanol, but which are separable by reverse-phase high pressure liquid chromatography. The same two products are formed by methanolysis of protein-bound phycocyanin chromophore, with the late-eluting one predominating. The two products derived from either phycocyanin methanolysis or cell extract incubation with biliverdin are partially interconvertible and they form the same ethylidine-free isomeric derivative, mesobiliverdin. Their absorption spectra correspond to those of the Z-and E-ethylidine isomers of phycocyanobilin. Based on previous work showing that the major methanolysis product has the E-ethylidine configuration, the other product of methanolysis and enzymic biliverdin transformation is therefore the Zethylidine isomer. The time course for formation of the two products during incubation suggests that the early-eluting product is the precursor of the late-eluting one. These results suggest that Z-ethylidine phycocyanobilin is the precursor of the E-ethylidine isomer, and that the latter may be a normal cellular precursor to protein-bound phycocyanin chromophore.

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Häm-Biosynthese aus L-Glutaminsäure

1984

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und nicht nur uber C-2 und C-4 verteilt. Demnach ist fur die Biosynthese von 1 eine aquilibrierende Zwischenstufe 10a-1Oc mit vier Sauerstoff-Substituenten anzunehmen.Wegen der uniformen Radioaktivitatsverteilung des nach Verfutterung von [2-I4C]Acetat erhaltenen Moniliformins 1* konnte eingewendet werden, daR die Acetateinheiten nicht direkt, sondern auf einem Umweg inkorporiert werden. In diesem Falle wiirde die spezifische Einbaurate jedoch weit unter der gefundenen (0.18%) liegen. Eine ahnliche Gleichverteilung der Radioaktivitat beobachteten wir auch bei einer in Anlehnung an die Biosynthese durchgefuhrten Totalsynthese von 1 * aus [l-14C]Ace-tatrR].

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Biosynthesis of Protoheme and Heme a Precursors Solely from Glutamate in the Unicellular Red Alga Cyanidium caldarium

Cited by 44 publications

References 16 publications

Biosynthesis of Protoheme and Heme a from Glutamate in Maize

Biosynthesis of Protoheme and Heme a from Glutamate in Maize

Enzymic Transformation of Biliverdin to Phycocyanobilin by Extracts of the Unicellular Red Alga Cyanidium caldarium

Häm-Biosynthese aus L-Glutaminsäure

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