Initial stages in the biosynthesis of porphyrins. 2. The formation of δ-aminolaevulic acid from glycine and succinyl-coenzyme A by particles from chicken erythrocytes

5-Aminolevulinic acid accumulated in the culture medium when Agmeneflum quadplicatum strain PR-6 was incubated in the presence of levulinic acid, a competitive inhibitor of 8-aminolevulinic acid dehydratase, and specifically labeled glutamate and glycine. The 8-aminolevulinic acid was purified using Dowex 50W-X8 and cleaved by periodate to yield succinic acid and formaldehyde. The distribution of radioactivity in the two fragments suggested that in blue-green algae the carbon skeleton of 8-aminolevulinic acid is derived directly from glutamate. However the possibility of the pathway of 8-aminolevulinic acid synthesis, from glycine and succinyl-coenzyme A also functioning in blue-green algae was not eliminated as uptake of glycine was minimal.&-Aminolevulinic acid is the first identified biosynthetic intermediate that is unique to the tetrapyrrole pathway. ALA2 is the precursor of heme in animals (16) and bacteria (9); of Chl in bacteria (6) and plants (8); and of the phycobilins in red algae (19). In many organisms ALA is formed by the condensation of glycine and succinyl-CoA, catalyzed by ALA synthetase, a pyridoxal-requiring enzyme. The enzymatic activity was first demonstrated in photosynthetic bacteria (12) and chicken erythrocytes (7). ALA synthetase has since been reported in yeast, bacteria, and a number of animal tissues. However, workers have been unable to demonstrate conclusively ALA synthetase activity in green plants and green algae (2).In studies in which cucumber cotyledons (3), bean and barley leaves (4), maize leaves (15), and the unicellular rhodophyte Cyanidium caldarium (10) were incubated in the presence of levulinic acid and labeled compounds; glutamate, a-ketoglutarate, and glutamine were found to donate label to the ALA that accumulated, much more effectively than glycine. Furthermore, from the specific pattern of incorporation of label into ALA, it appears that ALA is formed from the intact carbon skeleton of glutamate in a manner incompatible with the ALA synthetase route (1,5,10,15).Herein, we report the labeling of ALA from specifically labeled glutamate by a blue-green alga. The evidence suggests that bluegreen algae synthesize ALA from glutamate in a manner similar to that observed in green plants and green algae.

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confidence: 99%

Biosynthesis of δ-Aminolevulinic Acid from Glutamate in Agmenellum quadruplicatum

Kipe-Nolt¹,

Stevens²

1980

“…The universal biosynthetic precursor to hemes and Chl, ALA,2 can be formed by two routes: from the intact carbon skeleton of glutamate via a five-carbon pathway (4, 16), and by condensation of succinyl-CoA and glycine catalyzed by ALA synthase (succi-nyl-CoA:glycine C-succinyltransferase [decarboxylating] EC 2.3.1.37) (11,14). Animals and some bacteria, including photosynthetic bacteria, form ALA exclusively via ALA synthase (1 1,14,19).…”

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confidence: 99%

Biosynthesis of Protoheme and Heme a from Glutamate in Maize

Schneegurt

Beale²

1986

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.

“…Succin-i coenzvme A has been shown to be a precursor of porphvrins in animals and bacteria (1,6). The tracer studies of Shemin and Kumin (11) show-ed that duck ervthrocyte preparations Notuld incorporate label from the carboxvl carbons of succinate into hemile.…”

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confidence: 99%

“…Treatment with cycloheximide before illumination prevents the increase in activity. A number of other enzymes have been studied in an attempt to determine the significance of the transient nature of the changes in succinyl CoA synthetase activity.Succin-i coenzvme A has been shown to be a precursor of porphvrins in animals and bacteria (1,6 The previotus studies of succinyl CoA synthetase (E.C. 6.2.1.5 ) from plant sources have been concerned with the preparation of the isolated enzyme, its substrate and cofactor requirements and the reaction mechanism…”

mentioning

confidence: 99%

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Changes in Succinyl CoA Synthetase Activity in Etiolated Bean Leaves Caused by Illumination

Steer

Gibbs

1969

Abstract. The illumination of etiolated bean leaves (Phaseolus v2ulgaris) causes an increase in the activity of succinyl coenzyme A synthetase. Continuous white light or short periods of red or blue light followed by darkness will induce an increase with the highest activity at about 6 hr after the onset of illumination. Thereafter the activity decreases so that at 12 hr it is the same .as the initial dark activitv. Treatment with cycloheximide before illumination prevents the increase in activity. A number of other enzymes have been studied in an attempt to determine the significance of the transient nature of the changes in succinyl CoA synthetase activity.Succin-i coenzvme A has been shown to be a precursor of porphvrins in animals and bacteria (1,6 The previotus studies of succinyl CoA synthetase (E.C. 6.2.1.5 ) from plant sources have been concerned with the preparation of the isolated enzyme, its substrate and cofactor requirements and the reaction mechanism