Biosynthesis of porphyrins and related macrocycles. Part 41. Fate of oxygen atoms as precorrin-2 carrying eight labelled carboxyl groups (13C18O2H) is enzymatically converted into cobyrinic acid

Vishwakarma, Ram A.; Balachandran, Sarala; Alanine, Alex I.D.; Stamford, N. Patrick J.; Kiuchi, Fumiyuki; Leeper, Finian J.; Battersby, Alan R.

doi:10.1039/p19930002893

Cited by 21 publications

(7 citation statements)

References 6 publications

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“…71 This was further refined to show that the C-2 acetate had lost one oxygen atom by the time that cobyrinic acid had been synthesized. 72 Such an exchange of an oxygen would be consistent with the formation of a δ-lactone intermediate during the biosynthesis of the vitamin B 12 in this organism. No exchange of the carboxylic acid side chain oxygens would be expected in the "aerobic" biosynthesis of vitamin B 12 via the γ-lactone structure described in P. denitrificans (Fig.…”

Section: The Anaerobic Biosynthesis Of Adenosylcobyric Acidsupporting

confidence: 54%

The biosynthesis of adenosylcobalamin (vitamin B12)

et al. 2002

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Vitamin B12, or cobalamin, is one of the most structurally complex small molecules made in Nature. Major progress has been made over the past decade in understanding how this synthesis is accomplished. This review covers some of the most important findings that have been made and provides the reader with a complete description of the transformation of uroporphyrinogen III into adenosylcobalamin (AdoCbl). 183 references are cited.

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Section: The Anaerobic Biosynthesis Of Adenosylcobyric Acidsupporting

confidence: 54%

The biosynthesis of adenosylcobalamin (vitamin B12)

et al. 2002

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“…In Rhodobacter capsulatus the same reaction is catalyzed by a quite distinct enzyme called CobZ (78). The actual ringcontraction reaction is catalyzed by CobJ, which not only methylates the C17 position in a SAM-dependent fashion, but also contracts the macrocycle to leave the extruded methylated C20 carbon as an acetyl group attached to C1 (75,77,(79)(80)(81)(82). The product of this reaction is precorrin-4, which acts as the substrate for CobM that adds another SAM-derived methyl group to the macrocycle at C11 yielding precorrin-5 (83,84).…”

Section: The Aerobic Biosynthesis Of Cobalaminmentioning

confidence: 99%

Biosynthesis of the modified tetrapyrroles—the pigments of life

Bryant

Hunter

Warren

2020

Journal of Biological Chemistry

188

164

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Modified tetrapyrroles are large macrocyclic compounds, consisting of diverse conjugation and metal chelation systems and imparting an array of colors to the biological structures that contain them. Tetrapyrroles represent some of the most complex small molecules synthesized by cells and are involved in many essential processes that are fundamental to life on Earth, including photosynthesis, respiration, and catalysis. These molecules are all derived from a common template through a series of enzyme-mediated transformations that alter the oxidation state of the macrocycle and also modify its size, its side-chain composition, and the nature of the centrally chelated metal ion. The different modified tetrapyrroles include chlorophylls, hemes, siroheme, corrins (including vitamin B12), coenzyme F430, heme d1, and bilins. After nearly a century of study, almost all of the more than 90 different enzymes that synthesize this family of compounds are now known, and expression of reconstructed operons in heterologous hosts has confirmed that most pathways are complete. Aside from the highly diverse nature of the chemical reactions catalyzed, an interesting aspect of comparative biochemistry is to see how different enzymes and even entire pathways have evolved to perform alternative chemical reactions to produce the same end products in the presence and absence of oxygen. Although there is still much to learn, our current understanding of tetrapyrrole biogenesis represents a remarkable biochemical milestone that is summarized in this review.

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“…shermanii cobalt is inserted early into precorrin-3, which is ring-contracted without O 2 as cofactor (Scheme I), and at a later, unknown stage, a unique exchange of carbonyl oxygen at the C-27 (ring A) acetate occurs (6,7); this is another event that is not paralleled in aerobic metabolism (8). In this report, we describe the isolation of a new B 12 intermediate from Pr.…”

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Biosynthesis of vitamin B ₁₂ : Factor IV, a new intermediate in the anaerobic pathway

Wang

et al. 1996

Proc. Natl. Acad. Sci. U.S.A.

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The structure of a novel tetradehydrocorrin, factor IV, isolated from Propionibacterium shermanii has been established by multidimensional NMR spectroscopy. Incorporation of radiolabeled factor IV into cobyrinic acid established the biointermediacy of this cobalt complex, whose structure has implications for the mechanisms of the anaerobic pathway to B 12 .In the aerobic bacterium Pseudomonas denitrificans, the biosynthetic pathway to vitamin B 12 , featuring an oxygenrequiring step, has been established (for reviews, see refs. 1 and 2), but it is now clear that a second, anaerobic route to corrin has existed in nature for ca. 4 billion years (2, 3). Thus, the obligate anaerobes, such as methanogenic bacteria, and the semianaerobic Propionibacterium shermanii are able to synthesize B 12 by processes that differ at several pivotal steps from the aerobic pathway. The Ps. denitrificans route uses a twostage ring contraction sequence on the metal-free substrate precorrin-3, using O 2 (4) to fashion ␥-lactone and tertiary hydroxyl functions at C-1 and C-20 in precorrin-3x (Scheme I) as a prelude to a pinacol-like rearrangement, whereas cobalt is inserted late, i.e., not until all S-adenosylmethionine (AdoMet)-derived methyl groups are in place and amidation of the carboxylates has begun (1, 2).In contrast, it has been found (5) that in Pr. shermanii cobalt is inserted early into precorrin-3, which is ring-contracted without O 2 as cofactor (Scheme I), and at a later, unknown stage, a unique exchange of carbonyl oxygen at the C-27 (ring A) acetate occurs (6, 7); this is another event that is not paralleled in aerobic metabolism (8). In this report, we describe the isolation of a new B 12 intermediate from Pr. shermanii whose surprising structure provides circumstantial but compelling evidence for those mechanisms operating during anaerobic biosynthesis that mediate ring contraction and loss of the 2-carbon fragment from the western side. MATERIALS AND METHODSPreparation of Factor IV from epi-Factor II. A cell-free extract of Pr. shermanii (from 50 g of wet cells) was prepared by sonication (50 min at 0-4ЊC) in phosphate buffer (pH 7.6; 50 ml). Glutathione (5 mg), ATP (22 mg), NAD (5 mg), NADH (10 mg), AdoMet (75 mol), EDTA (3.5 mol), Co 2ϩ (4 mol), and Co 3ϩ (1.8 mol) were added to the supernatant of the centrifuged suspension (17,000 ϫ g; 25 min at OЊC). For preparative isolation, 3-epi; 8-epi factor II ( Fig. 1; 500 mol) was added, and the incubation was carried out at 31ЊC for 16 hr. Sodium cyanide (5 mg) was then added, and the tetrapyrrolic mixture was adsorbed on DEAE-Sephadex A-25 (Pharmacia) followed by extraction and esterification by MeOH͞

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Biosynthesis of porphyrins and related macrocycles. Part 41. Fate of oxygen atoms as precorrin-2 carrying eight labelled carboxyl groups (13C18O2H) is enzymatically converted into cobyrinic acid

Cited by 21 publications

References 6 publications

The biosynthesis of adenosylcobalamin (vitamin B12)

The biosynthesis of adenosylcobalamin (vitamin B12)

Biosynthesis of the modified tetrapyrroles—the pigments of life

Biosynthesis of vitamin B ₁₂ : Factor IV, a new intermediate in the anaerobic pathway

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Biosynthesis of porphyrins and related macrocycles. Part 41. Fate of oxygen atoms as precorrin-2 carrying eight labelled carboxyl groups (13C18O2H) is enzymatically converted into cobyrinic acid

Cited by 21 publications

References 6 publications

The biosynthesis of adenosylcobalamin (vitamin B12)

The biosynthesis of adenosylcobalamin (vitamin B12)

Biosynthesis of the modified tetrapyrroles—the pigments of life

Biosynthesis of vitamin B 12 : Factor IV, a new intermediate in the anaerobic pathway

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Biosynthesis of vitamin B ₁₂ : Factor IV, a new intermediate in the anaerobic pathway