Vitamin B12: Insights into Biosynthesis's Mount Improbable

Raux, Evelyne; Schubert, Heidi; Roper, J. M.; Wilson, K.S.; Warren, Martin J.

doi:10.1006/bioo.1998.1125

Cited by 46 publications

(41 citation statements)

References 71 publications

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“…1. ) [49,70]. W przypadku pochodnych cyjanokobalaminy mogą występować różne ligandy kowalentnie związane z atomem kobaltu nad lub pod strukturą pierścienia makrocyklicznego.…”

Section: Budowa Witaminy B 12unclassified

Vitamin B 12 - Structure, Biosynthesis , Functions, and Methods of Determination

Kośmider¹,

Czaczyk²

2010

ZNTJ

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S t r e s z c z e n i e W niniejszej pracy przedstawiono aktualną wiedzę dotyczącą witaminy B 12 (kobalaminy), struktury i szlaków metabolicznych jej powstawania, znaczenia dla zdrowia człowieka oraz metod jej wykrywania. Przedstawiono także wyniki badań nad biotechnologiczną produkcją witaminy B 12 . Witamina B 12 jest istotnym kofaktorem w metabolizmie węglowodanów, tłuszczów, aminokwasów oraz kwasów nukleinowych w organizmie człowieka. Zapobiega także występowaniu anemii złośliwej. Biosynteza kobalaminy jest domeną wyłącznie organizmów prokariotycznych. Wiele gatunków bakterii jest zdolnych do produkcji witaminy B 12 , ale tylko dwa mają istotne znaczenie: Propionibacteriumm freudenreichii i Pseudomonas denitrificans.

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“…1. ) [49,70]. W przypadku pochodnych cyjanokobalaminy mogą występować różne ligandy kowalentnie związane z atomem kobaltu nad lub pod strukturą pierścienia makrocyklicznego.…”

Section: Budowa Witaminy B 12unclassified

Vitamin B 12 - Structure, Biosynthesis , Functions, and Methods of Determination

Kośmider¹,

Czaczyk²

2010

ZNTJ

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“…The methyl groups are added by the activation of a single methyltransferase that is able to catalyze the addition to C-2 and C-7 positions, and the methyl groups are derived from (S)-adenosyl-Lmethionine (SAM) [59,74]. At precorrin-2 the two pathways for vitamin B 12 biosynthesis are diverged [55]. The oxygen-dependent and independent pathways for vitamin B 12 biosynthesis are quite distinct: the oxygen-independent part of the pathway starts with the insertion of cobalt into precorrin-2, while this chelation reaction in the oxygen-dependent part occurs only after nine further reaction steps.…”

Section: Biosynthetic Pathway Of Vitamin B 12mentioning

confidence: 99%

Production of tetrapyrrole compounds and vitamin B12 using genetically engineering of Propionibacterium freudenreichii. An overview

Murooka

Piao

Kiatpapan

et al. 2005

Lait

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-Propionibacterium freudenreichii is a commercially important bacterium that is used in the production of cheeses, cobalamin (vitamin B 12 ) and propionic acid. Metabolic engineering using genetically improved strains will make the fermentation process more economical and also enhance the quality of the products. Host-vector systems and expression vectors using strong promoters from P. freudenreichii were developed in propionibacteria. By using these expression vectors and amplification of various genes, productions of 5-aminolevulinic acid, tetrapyrrole compounds and vitamin B 12 were reported. Here, we review the advancement of genetic engineering in P. freudenreichii in recent years, covering the molecular aspects of the formation of tetrapyrrole compounds and vitamin B12.

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“…1), which is synthesized by one of the most elaborate and complex biosynthetic pathways known in biological systems requiring somewhere around thirty enzymatic steps for its complete de novo synthesis (5). Cobalamin biosynthesis is further complicated by the presence of two similar though biochemically distinct pathways that are referred to as the aerobic and anaerobic routes (7)(8)(9)(10). These pathways differ in their requirement for molecular oxygen and the timing of cobalt insertion.…”

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confidence: 99%

Demonstration That CobG, the Monooxygenase Associated with the Ring Contraction Process of the Aerobic Cobalamin (Vitamin B12) Biosynthetic Pathway, Contains an Fe-S Center and a Mononuclear Non-heme Iron Center

Schroeder

Lawrence

Biedendieck

et al. 2009

Journal of Biological Chemistry

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The ring contraction process that occurs during cobalamin (vitamin B 12 ) biosynthesis is mediated via the action of two enzymes, CobG and CobJ. The first of these generates a tertiary alcohol at the C-20 position of precorrin-3A by functioning as a monooxygenase, a reaction that also forms a gamma lactone with the acetic acid side chain on ring A. The product, precorrin-3B, is then acted upon by CobJ, which methylates at the C-17 position and promotes ring contraction of the macrocycle by catalyzing a masked pinacol rearrangement. Here, we report the characterization of CobG enzymes from Pseudomonas denitrificans and Brucella melitensis. We show that both contain a [4Fe-4S] center as well as a mononuclear non-heme iron. Although both enzymes are active in vivo, the P. denitrificans enzyme was found to be inactive in vitro. Further analysis of this enzyme revealed that the mononuclear non-heme iron was not reducible, and it was concluded that it is rapidly inactivated once it is released from the bacterial cell. In contrast, the B. melitensis enzyme was found to be fully active in vitro and the mononuclear non-heme iron was reducible by dithionite. The reduced mononuclear non-heme was able to react with the oxygen analogue NO, but only in the presence of the substrate precorrin-3A. The cysteine residues responsible for binding the Fe-S center were identified by site-directed mutagenesis. A mechanism for CobG is presented.

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Vitamin B12: Insights into Biosynthesis's Mount Improbable

Cited by 46 publications

References 71 publications

Vitamin B 12 - Structure, Biosynthesis , Functions, and Methods of Determination

Vitamin B 12 - Structure, Biosynthesis , Functions, and Methods of Determination

Production of tetrapyrrole compounds and vitamin B12 using genetically engineering of Propionibacterium freudenreichii. An overview

Demonstration That CobG, the Monooxygenase Associated with the Ring Contraction Process of the Aerobic Cobalamin (Vitamin B12) Biosynthetic Pathway, Contains an Fe-S Center and a Mononuclear Non-heme Iron Center

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