Vitamin B12 and the synthesis of the methyl groups of choline in ochromonas malhamensis

Lust, George; Daniel, Louise J.

doi:10.1016/0003-9861(64)90422-9

Cited by 11 publications

(5 citation statements)

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“…The origin of the methyl groups from S-adenosylmethionine appears established by our labeling data with [methyl-l4C]methionine in vivo. It is interesting that Lust and Daniel established this reaction for the biosynthesis of phosphatidylcholine in Ochromonas malhamensis (Lust and Daniel. 1964): it is not clear if their procedure would have picked up any labeled derivative of lipid A, if this lipid indeed is present in this close relative of Ochromonas danica.…”

Section: Discussionmentioning

confidence: 99%

Isolation and characterization of a novel lipid, 1(3),2-diacylglyceryl-(3)-O-4'-(N,N,N-trimethyl)homoserine, from Ochromonas danica

Brown¹,

Elovson²

1974

Biochemistry

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Section: Discussionmentioning

confidence: 99%

Isolation and characterization of a novel lipid, 1(3),2-diacylglyceryl-(3)-O-4'-(N,N,N-trimethyl)homoserine, from Ochromonas danica

Brown¹,

Elovson²

1974

Biochemistry

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“…tumefaciens is consistent with the hypothesis that organisms which are capable of facile synthesis of methyl groups would not reutilize choline for PC synthesis via CDP-choline. It has been shown that methionine serves as a good methyl-group donor for PC synthesis in 0. malhamensis ( 20) ; however, this organism, unlike Euglena, requires methionine for optimum growth (1). It would be of interest to determine whether or not 0. malhamensis conserves choline by means of the CDP-choline route of PC synthesis.…”

Section: Discussionmentioning

confidence: 99%

Biosynthesis of Phosphatidylcholine in Euglena gracilis*†

Tipton

Swords

1966

The Journal of Protozoology

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SYNOPSIS. Extracts of Euglena gracilis carry out a very rapid but limited synthesis of phosphatidylcholine when S-adenosylmethionine or A T P and methionine are supplied. Cytidinediphosphocholine ap-HE biosynthesis of phosphatidylcholine (PC) has been T well characterized with respect to the nature of the precursors and intermediate compounds in higher animals. Two pathways are found in a variety of animal tissues: ( a ) phosphocholine is transferred from cytidinediphosphocholine to Il2-diglyceride to form PC and cytidylic acid( 1 8~9 ) ; ( b ) phosphatidylethanolamine (PE) is methylated in 3 successive reactions with S-adenosylmethionine as the methylgroup donor (3,4,5,7,8,10,12).Although most animal tissues have a greater capacity to synthesize PC by the CDP-choline pathway than by methylation of PE (4), it appears that all the choline produced in the animal body arises through methylation of PE (7); at any rate, no other means of synthesizing choline in animals is now known. The CDP-choline pathway apparently serves to conserve methyl groups in the animal body. Synthesis of PC from CDP-choline has not been shown to occur outside the animal kingdom.The methylation pathway has been clearly shown in Agrobacterium tumefaciens( 17), and there is good circumstantial evidence that it functions in the mold Neurospora crassa( 13). The photosynthetic protozoon Ochromonas malhamensis has been shown to produce lipid-bound C14labeled choline from C14-methionine( 20), again indicating operation of the methylation pathway. A . tumefaciens will utilize exogenous choline for lipid synthesis, but attempts to find enzymes of the CDP-choline pathway were unsuccessful (22). Choline is also utilized by Neurospora for phospholipid synthesis, but the enzymatic steps were not examined ( 1 1 ) .Phospholipid metabolism has been studied very little in plants and the photosynthetic protozoa. In the work described here, attempts were made to find PC synthesis in extracts of Euglena gracilis, using the substrates of both the CDP-choline pathway and the methylation pathway. MATERIALS AND METHODSCDP-choline, BSA and Tris buffer were obtained from Sigma Chemical Co., St. Louis, Mo. ; L-methionine hydrochloride, egg lecithin, and lipase (Steapsin) from Nutritional Biochemicals Corp., Cleveland, Ohio ; and (-) -S-adenosyl-L-methionine iodide (84.1%

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“…The fact that homocysteine stimulated formate-CI4 utilization is in accord with the hypothesis that methionine synthesis precedes cholinemethyl group synthesis. This is further corroborated by the fact that vitamin BIZ has been shown to exert a marked stimulation in this reaction sequence in 0. maEhamensis ( 18).…”

Section: Discussionmentioning

confidence: 99%

“…The method of assaying for phospholipid-choline-C"H3 has been described ( 18). In some experiments choline was degraded to trimethylamine and precipitated as the reineckate by the method of Artom & Crowder as quoted by Artom (5).…”

Section: Ochromonas Malhamensismentioning

confidence: 99%

“…In the present study various methyl-group precursors were used in order to establish the origin of the methyl groups of choline in the fresh-water chrysomonad, Ochromonas malhamensis. (11532) was obtained from the American Type Culture Collection, Washington, D. C. The culturing and preparation of 0. malhamensis cells were carried out as described previously ( 18).…”

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confidence: 99%

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Studies on the Origin of the Methyl Groups of Choline in *Ochromonas malhamensis**

Lust¹,

Daniel

1966

The Journal of Protozoology

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SYNOPSIS. Five‐ to 6‐day‐old resting cells of Ochromonas malhamensis were incubated at pH 6.5 with glucose and appropriate C14 precursors of the methyl groups of phospholipid‐choline. Under the experimental conditions L‐methionine‐C14H3 was the most efficient source of choline‐methyl groups, followed by formate‐C14, formaldehyde‐C14 and DL‐serine‐3‐C14, respectively. Glycine‐2‐C14 was not incorporated into choline. Both L‐methionine‐C14H3 and formate‐C14 served as precursors for the methyl groups of monomethylethanolamine, dimethylethanolamine and choline. Addition of non‐radio‐active L‐methionine depressed the incorporation of formate‐C14 into choline‐methyl groups by 50%. The results support the hypothesis that methionine can be the source of all 3 methyl groups of choline, and that formate is probably converted to the methyl group of methionine before transmethylation to choline. However, an alternate pathway from single‐carbon sources cannot be excluded.

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Vitamin B12 and the synthesis of the methyl groups of choline in ochromonas malhamensis

Cited by 11 publications

References 19 publications

Isolation and characterization of a novel lipid, 1(3),2-diacylglyceryl-(3)-O-4'-(N,N,N-trimethyl)homoserine, from Ochromonas danica

Isolation and characterization of a novel lipid, 1(3),2-diacylglyceryl-(3)-O-4'-(N,N,N-trimethyl)homoserine, from Ochromonas danica

Biosynthesis of Phosphatidylcholine in Euglena gracilis*†

Studies on the Origin of the Methyl Groups of Choline in *Ochromonas malhamensis**

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Vitamin B12 and the synthesis of the methyl groups of choline in ochromonas malhamensis

Cited by 11 publications

References 19 publications

Isolation and characterization of a novel lipid, 1(3),2-diacylglyceryl-(3)-O-4'-(N,N,N-trimethyl)homoserine, from Ochromonas danica

Isolation and characterization of a novel lipid, 1(3),2-diacylglyceryl-(3)-O-4'-(N,N,N-trimethyl)homoserine, from Ochromonas danica

Biosynthesis of Phosphatidylcholine in Euglena gracilis*†

Studies on the Origin of the Methyl Groups of Choline in Ochromonas malhamensis*

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Studies on the Origin of the Methyl Groups of Choline in *Ochromonas malhamensis**