- Noncanonical coproporphyrin-dependent bacterial heme biosynthesis pathway that does not use protoporphyrin
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It has been generally accepted that biosynthesis of protoheme (heme) uses a common set of core metabolic intermediates that includes protoporphyrin. Herein, we show that the Actinobacteria and Firmicutes (high-GC and low-GC Gram-positive bacteria) are unable to synthesize protoporphyrin. Instead, they oxidize coproporphyrinogen to coproporphyrin, insert ferrous iron to make Fecoproporphyrin (coproheme), and then decarboxylate coproheme to generate protoheme. This pathway is specified by three genes named hemY, hemH, and hemQ. The analysis of 982 representative prokaryotic genomes is consistent with this pathway being the most ancient heme synthesis pathway in the Eubacteria. Our results identifying a previously unknown branch of tetrapyrrole synthesis support a significant shift from current models for the evolution of bacterial heme and chlorophyll synthesis. Because some organisms that possess this coproporphyrin-dependent branch are major causes of human disease, HemQ is a novel pharmacological target of significant therapeutic relevance, particularly given high rates of antimicrobial resistance among these pathogens.
- Dailey, Harry A.,Gerdes, Svetlana,Dailey, Tamara A.,Burch, Joseph S.,Phillips, John D.
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p. 2210 - 2215
(2015/04/21)
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- Abiotic formation of uroporphyrinogen and coproporphyrinogen from acyclic reactants
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Tetrapyrrole macrocycles (e.g., porphyrins) have long been proposed as key ingredients in the emergence of life, yet plausible routes for forming their essential pyrrole precursor have previously not been identified. Here, the anaerobic reaction of δ-aminolevulinic acid (ALA, 5-240 mM) with 5-methoxy-3-(methoxyacetyl)levulinic acid (1-AcOH, 5-240 mM) in water (pH 5-7) at 25-85°C for a few hours to a few days affords uroporphyrinogen, which upon chemical oxidation gives uroporphyrin in overall yield of up to 10%. The key intermediate is the α-methoxymethyl-substituted analogue of the pyrrole porphobilinogen (PBG). Reaction of ALA and the decarboxy analogue of 1-AcOH (1-Me) gave coproporphyrinogen (without its biosynthetic precursor uroporphyrinogen as an intermediate); oxidation gave the corresponding coproporphyrin in yields comparable to those for uroporphyrin. In each case a mixture of porphyrin isomers was obtained, consistent with reversible oligopyrromethane formation. The route investigated here differs from the universal extant biosynthetic pathway to tetrapyrrole macrocycles, where uroporphyrinogen (isomer III) - nature's last common precursor to corrins, heme, and chlorophylls - is derived from eight molecules of ALA (via four molecules of PBG). The demonstration of the spontaneous self-organization of eight acyclic molecules to form the porphyrinogen under simple conditions may open the door to the development of a chemical model for the prebiogenesis of tetrapyrrole macrocycles. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2011.
- Lindsey, Jonathan S.,Chandrashaker, Vanampally,Taniguchi, Masahiko,Ptaszek, Marcin
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supporting information; scheme or table
p. 65 - 75
(2011/04/14)
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- The oxygen-independent coproporphyrinogen III oxidase HemN utilizes harderoporphyrinogen as a reaction intermediate during conversion of coproporphyrinogen III to protoporphyrinogen IX
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During heme biosynthesis the oxygen-independent coproporphyrinogen III oxidase HemN catalyzes the oxidative decarboxylation of the two propionate side chains on rings A and B of coproporphyrinogen III to the corresponding vinyl groups to yield protoporphyrinogen IX. Here, the sequence of the two decarboxylation steps during HemN catalysis was investigated. A reaction intermediate of HemN activity was isolated by HPLC analysis and identified as monovinyltripropionic acid porphyrin by mass spectrometry. This monovinylic reaction intermediate exhibited identical chromatographic behavior during HPLC analysis as harderoporphyrin (3-vinyl-8,13,17-tripropionic acid-2,7,12,18- tetramethylporphyrin). Furthermore, HemN was able to utilize chemically synthesized harderoporphyrinogen as substrate and converted it to protoporphyrinogen IX. These results suggest that during HemN catalysis the propionate side chain of ring A of coproporphyrinogen III is decarboxylated prior to that of ring B. by Walter de Gruyter.
- Rand, Katrin,Noll, Claudia,Schiebel, Hans Martin,Kemken, Dorit,Duelcks, Thomas,Kalesse, Markus,Heinz, Dirk W.,Layer, Gunhild
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experimental part
p. 55 - 63
(2011/11/05)
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- Studies on the formation of porphyrinogens from monopyrroles in presence of the enzymes PBG deaminase and/or Uro'gen III synthase
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The substrate-specificities of two enzymes in the biosynthetic pathway to vitamin B12, PBG deaminase and Uro'gen III synthase, which are involved in the formation of Uro'gen III from the pyrrole PBG, are investigated for the preparation of Uroporphyrin analogs. Both enzymes display strong substrate-specificity. However, tetramerization of pyrroles with carboxylate β-substituents in mildly basic buffer represents the best and most rapid route to a family of Uro I analogs for enzymatic activity studies.
- Pichon-Santander, Clotilde,Ian Scott
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p. 8669 - 8672
(2007/10/03)
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- Biosynthesis of Porphyrins and Related Macrocycles. Part 15. Chemical and Enzymic Formation of Uroporphyrinogen Isomers from Unrearranged Aminomethylpyrromethane: Separation of Isomeric Coproporphyrin Esters
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The unrearranged pyrromethane (1) is transformed chemically mainly into uro'gen-I with a smaller amount of uro'gen-IV but only traces of uro'gen-III are formed.Uro'gen-I is produced via a tetrapyrrolic (bilane) intermediate and when the diaminase-cosynthetase enzyme system from Euglena gracilis is present, this intermediate is converted into uro'gen-III.The rearrangement step for this conversion has the same characteristics found earlier for the natural biosynthetic process from porphobilinogen.Pyrromethane (1) is not a direct biosynthetic precursor of uro'gen-III and reasons are advanced why this is understandable.Methods are developed based on high pressure liquid chromatography for the separation of all four isomeric coproporphyrin esters.
- Battersby, Alan R.,Buckley, Dennis G.,Johnson, Dawid W.,Mander, Lewis N.,McDonald, Edward,Williams, D. Clive
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p. 2779 - 2785
(2007/10/02)
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