Terminal steps of haem biosynthesis

2002 ◽  
Vol 30 (4) ◽  
pp. 590-595 ◽  
Author(s):  
H. A. Dailey
Keyword(s):  
Crystal Structure ◽  
Bacillus Subtilis ◽  
Ferrous Iron ◽  
Protoporphyrin Ix ◽  
Oxidative Decarboxylation ◽  
Protoporphyrinogen Oxidase ◽  
Coproporphyrinogen Oxidase ◽  
Cellular Location ◽  
Haem Biosynthesis ◽  
Small Set

The terminal three steps in haem biosynthesis are the oxidative decarboxylation of coproporphyrinogen III to protoporphyrinogen IX, followed by the six-electron oxidation of protoporphyrinogen to protoporphyrin IX, and finally the insertion of ferrous iron to form haem. Interestingly, Nature has evolved distinct enzymic machinery to deal with the antepenultimate (co-proporphyrinogen oxidase) and penultimate (protoporphyrinogen oxidase) steps for aerobic compared with anaerobic organisms. The terminal step is catalysed by the enzyme ferrochelatase. This enzyme is clearly conserved with regard to a small set of essential catalytic residues, but varies significantly with regard to size, subunit composition, cellular location and the presence or absence of a [2Fe-2S] cluster. Coproporphyrinogen oxidase and protoporphyrinogen oxidase are reviewed with regard to their enzymic and physical characteristics. Ferrochelatase, which is the best characterized of these three enzymes, will be described with particular emphasis paid to what has been learned from the crystal structure of the Bacillus subtilis and human enzymes.

Measurement of ferrochelatase activity using a novel assay suggests that plastids are the major site of haem biosynthesis in both photosynthetic and non-photosynthetic cells of pea (Pisum sativum L.)

2002 ◽  
Vol 362 (2) ◽  
pp. 423-432 ◽  
Author(s):  
Johanna E. CORNAH ◽  
Jennifer M. ROPER ◽  
Davinder Pal SINGH ◽  
Alison G. SMITH
Keyword(s):  
Ferrous Iron ◽  
Specific Activity ◽  
Higher Plants ◽  
Protoporphyrin Ix ◽  
Chlorophyll Synthesis ◽  
Marker Enzyme ◽  
Hexane Extraction ◽  
Higher Plant ◽  
Major Site ◽  
Haem Biosynthesis

Ferrochelatase is the terminal enzyme of haem biosynthesis, catalysing the insertion of ferrous iron into the macrocycle of protoporphyrin IX, the last common intermediate of haem and chlorophyll synthesis. Its activity has been reported in both plastids and mitochondria of higher plants, but the relative amounts of the enzyme in the two organelles are unknown. Ferrochelatase is difficult to assay since ferrous iron requires strict anaerobic conditions to prevent oxidation, and in photosynthetic tissues chlorophyll interferes with the quantification of the product. Accordingly, we developed a sensitive fluorimetric assay for ferrochelatase that employs Co2+ and deuteroporphyrin in place of the natural substrates, and measures the decrease in deuteroporphyrin fluorescence. A hexane-extraction step to remove chlorophyll is included for green tissue. The assay is linear over a range of chloroplast protein concentrations, with an average specific activity of 0.68nmol·min−1·mg of protein−1, the highest yet reported. The corresponding value for mitochondria is 0.19nmol·min−1·mg of protein−1. The enzyme is inhibited by N-methylprotoporphyrin, with an estimated IC50 value of ≈ 1nM. Using this assay we have quantified ferrochelatase activity in plastids and mitochondria from green pea leaves, etiolated pea leaves and pea roots to determine the relative amounts in the two organelles. We found that, in all three tissues, greater than 90% of the activity was associated with plastids, but ferrochelatase was reproducibly detected in mitochondria, at levels greater than the contaminating plastid marker enzyme, and was latent. Our results indicate that plastids are the major site of haem biosynthesis in higher plant cells, but that mitochondria also have the capacity for haem production.

scholarly journals Multiple mechanisms for the regulation of haem synthesis during erythroid cell differentiation. Possible role for coproporphyrinogen oxidase

1991 ◽  
Vol 275 (2) ◽  
pp. 321-326 ◽  
Author(s):  
L H Conder ◽  
S I Woodard ◽  
H A Dailey
Keyword(s):  
De Novo ◽  
Culture Media ◽  
Reductase Activity ◽  
Erythroid Cell ◽  
Erythroid Precursor ◽  
Protoporphyrinogen Oxidase ◽  
Coproporphyrinogen Oxidase ◽  
Haem Biosynthesis ◽  
Erythroid Cell Differentiation ◽  
Iron Reductase

Murine erythroleukaemia (MEL) cells are virus-transformed erythroid precursor cells that, when induced to differentiate by dimethyl sulphoxide (DMSO), will initiate haem biosynthesis by the induction and synthesis de novo of all of the enzymes of the haem-biosynthetic pathway. The activities of porphobilinogen (PBG) deaminase (EC 4.3.1.8), coproporphyrinogen oxidase (EC 1.3.3.3), protoporphyrinogen oxidase (EC 1.3.3.4), ferrochelatase (EC 4.99.1.1) and NADH:ferric iron reductase, as well as the synthesis of the enzyme ferrochelatase and the levels of excreted porphyrins, were monitored during DMSO-induced differentiation of MEL cells in culture. The data demonstrate that PBG deaminase and protoporphyrinogen oxidase activities rise rapidly and early, in comparison with ferrochelatase activity, which rises more slowly, and coproporphyrinogen oxidase activity, which decreases by 60% within 24 h of induction before returning to initial levels by 72 h. NADH:ferric iron reductase activity increases slightly, but is always present at levels higher than needed for haem synthesis. Total immunoprecipitable ferrochelatase also rises slowly and parallels the increase in its activity, suggesting that it is not synthesized early in a slowly processed precursor form. Examination of culture media demonstrated that, whereas excretion of protoporphyrin and coproporphyrin occurs within 24 h of induction, coproporphyrin is excreted in amounts 4-15 times greater than protoporphyrin.

scholarly journals The coproporphyrin ferrochelatase of Staphylococcus aureus: mechanistic insights into a regulatory iron-binding site

2017 ◽  
Vol 474 (20) ◽  
pp. 3513-3522 ◽  
Author(s):  
Charlie Hobbs ◽  
James D. Reid ◽  
Mark Shepherd
Keyword(s):  
Staphylococcus Aureus ◽  
Ferrous Iron ◽  
Substrate Inhibition ◽  
Iron Concentration ◽  
Protoporphyrin Ix ◽  
Site Directed Mutagenesis ◽  
Bacterial Phyla ◽  
Haem Biosynthesis ◽  
And Staphylococcus Aureus ◽  
Dependent Pathway

The majority of characterised ferrochelatase enzymes catalyse the final step of classical haem synthesis, inserting ferrous iron into protoporphyrin IX. However, for the recently discovered coproporphyrin-dependent pathway, ferrochelatase catalyses the penultimate reaction where ferrous iron is inserted into coproporphyrin III. Ferrochelatase enzymes from the bacterial phyla Firmicutes and Actinobacteria have previously been shown to insert iron into coproporphyrin, and those from Bacillus subtilis and Staphylococcus aureus are known to be inhibited by elevated iron concentrations. The work herein reports a Km (coproporphyrin III) for S. aureus ferrochelatase of 1.5 µM and it is shown that elevating the iron concentration increases the Km for coproporphyrin III, providing a potential explanation for the observed iron-mediated substrate inhibition. Together, structural modelling, site-directed mutagenesis, and kinetic analyses confirm residue Glu271 as being essential for the binding of iron to the inhibitory regulatory site on S. aureus ferrochelatase, providing a molecular explanation for the observed substrate inhibition patterns. This work therefore has implications for how haem biosynthesis in S. aureus is regulated by iron availability.

scholarly journals PPO-Inhibiting Herbicides and Structurally Relevant Schiff Bases: Evaluation of Inhibitory Activities against Human Protoporphyrinogen Oxidase

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 383
Author(s):  
Milan Jakubek ◽  
Michal Masařík ◽  
Tomáš Bříza ◽  
Robert Kaplánek ◽  
Kateřina Veselá ◽  
...  
Keyword(s):  
Melting Temperature ◽  
Schiff Bases ◽  
Anticancer Agents ◽  
Protoporphyrin Ix ◽  
Docking Study ◽  
Structural Motif ◽  
Protoporphyrinogen Oxidase ◽  
Ic50 Values ◽  
Inhibitory Activities ◽  
Potential Inhibitors

The study of human protoporphyrinogen oxidase (hPPO) inhibition can contribute significantly to a better understanding of some pathogeneses (e.g., porphyria, herbicide exposure) and the development of anticancer agents. Therefore, we prepared new potential inhibitors with Schiff base structural motifs (2-hydroxybenzaldehyde-based Schiff bases 9–13 and chromanone derivatives 17–19) as structurally relevant to PPO herbicides. The inhibitory activities (represented by the half maximal inhibitory concentration (IC50) values) and enzymatic interactions (represented by the hPPO melting temperatures) of these synthetic compounds and commercial PPO herbicides used against hPPO were studied by a protoporphyrin IX fluorescence assay. In the case of PPO herbicides, significant hPPO inhibition and changes in melting temperature were observed for oxyfluorten, oxadiazon, lactofen, butafenacil, saflufenacil, oxadiargyl, chlornitrofen, and especially fomesafen. Nevertheless, the prepared compounds did not display significant inhibitory activity or changes in the hPPO melting temperature. However, a designed model of hPPO inhibitors based on the determined IC50 values and a docking study (by using AutoDock) found important parts of the herbicide structural motif for hPPO inhibition. This model could be used to better predict PPO herbicidal toxicity and improve the design of synthetic inhibitors.

Crystal Structure of Urate Oxidase from Bacillus Subtilis 168

2019 ◽  
Vol 64 (7) ◽  
pp. 1126-1133 ◽  
Author(s):  
A. Nayab ◽  
S. A. Moududee ◽  
Y. Shi ◽  
Y. Jiang ◽  
Q. Gong
Keyword(s):  
Crystal Structure ◽  
Bacillus Subtilis ◽  
Urate Oxidase ◽  
Bacillus Subtilis 168

scholarly journals Crystal Structure of Bacillus subtilis Guanine Deaminase

2004 ◽  
Vol 279 (34) ◽  
pp. 35479-35485 ◽  
Author(s):  
Shwu-Huey Liaw ◽  
Yu-Jui Chang ◽  
Cheng-Tsung Lai ◽  
Hui-Chuan Chang ◽  
Gu-Gang Chang
Keyword(s):  
Crystal Structure ◽  
Bacillus Subtilis ◽  
Guanine Deaminase

Preparation, Characterisation, Crystal Structure and Antibacterial Activity of two Bis-Schiff Bases Containing a Piperazine Ring

2018 ◽  
Vol 42 (10) ◽  
pp. 512-514
Author(s):  
Rui-bo Xu ◽  
Xiao-tian Yang ◽  
Hai-nan Li ◽  
Peng-cheng Zhao ◽  
Jiao-jiao Li ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Antibacterial Activity ◽  
Bacillus Subtilis ◽  
Schiff Bases ◽  
Piperazine Ring ◽  
X Ray ◽  
X Ray Crystallography ◽  
Good Antibacterial Activity

Two new bis-Schiff bases containing a piperazine ring, N,N‘-bis(4-chlorobenzylidene)- and N,N‘-bis(4-cyanobenzylidene)-1,4-bis(3-aminopropyl)piperazine, were prepared by the reaction of N,N‘-bis(3-aminopropyl)piperazine with 4-chloro- and 4-cyanobenzaldehyde, respectively. The dichloro compound was fully identified by X-ray crystallography and it exhibited good antibacterial activity against Escherichia coli, Staphylococcus aureus and Bacillus subtilis.

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