Thiaville2016 - Folate pathway model (PanB overexpression and THF regulation)

  public model
Model Identifier
BIOMD0000000690
Short description
Henry2016 Folate pathway model with induced PanB reaction

This model is described in the article:

Thiaville JJ, Frelin O, García-Salinas C, Harrison K, Hasnain G, Horenstein NA, Díaz de la Garza RI, Henry CS, Hanson AD, de Crécy-Lagard V.
Front Microbiol 2016; 7: 431

Abstract:

Tetrahydrofolate (THF) and its one-carbon derivatives, collectively termed folates, are essential cofactors, but are inherently unstable. While it is clear that chemical oxidation can cleave folates or damage their pterin precursors, very little is known about enzymatic damage to these molecules or about whether the folate biosynthesis pathway responds adaptively to damage to its end-products. The presence of a duplication of the gene encoding the folate biosynthesis enzyme 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase (FolK) in many sequenced bacterial genomes combined with a strong chromosomal clustering of the folK gene with panB, encoding the 5,10-methylene-THF-dependent enzyme ketopantoate hydroxymethyltransferase, led us to infer that PanB has a side activity that cleaves 5,10-methylene-THF, yielding a pterin product that is recycled by FolK. Genetic and metabolic analyses of Escherichia coli strains showed that overexpression of PanB leads to accumulation of the likely folate cleavage product 6-hydroxymethylpterin and other pterins in cells and medium, and-unexpectedly-to a 46% increase in total folate content. In silico modeling of the folate biosynthesis pathway showed that these observations are consistent with the in vivo cleavage of 5,10-methylene-THF by a side-activity of PanB, with FolK-mediated recycling of the pterin cleavage product, and with regulation of folate biosynthesis by folates or their damage products.

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Format
SBML (L2V4)
Related Publication
  • Experimental and Metabolic Modeling Evidence for a Folate-Cleaving Side-Activity of Ketopantoate Hydroxymethyltransferase (PanB).
  • Thiaville JJ, Frelin O, García-Salinas C, Harrison K, Hasnain G, Horenstein NA, Díaz de la Garza RI, Henry CS, Hanson AD, de Crécy-Lagard V
  • Frontiers in microbiology , 0/ 2016 , Volume 7 , pages: 431 , PubMed ID: 27065985
  • Department of Microbiology and Cell Science, University of Florida Gainesville, FL, USA.
  • Tetrahydrofolate (THF) and its one-carbon derivatives, collectively termed folates, are essential cofactors, but are inherently unstable. While it is clear that chemical oxidation can cleave folates or damage their pterin precursors, very little is known about enzymatic damage to these molecules or about whether the folate biosynthesis pathway responds adaptively to damage to its end-products. The presence of a duplication of the gene encoding the folate biosynthesis enzyme 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase (FolK) in many sequenced bacterial genomes combined with a strong chromosomal clustering of the folK gene with panB, encoding the 5,10-methylene-THF-dependent enzyme ketopantoate hydroxymethyltransferase, led us to infer that PanB has a side activity that cleaves 5,10-methylene-THF, yielding a pterin product that is recycled by FolK. Genetic and metabolic analyses of Escherichia coli strains showed that overexpression of PanB leads to accumulation of the likely folate cleavage product 6-hydroxymethylpterin and other pterins in cells and medium, and-unexpectedly-to a 46% increase in total folate content. In silico modeling of the folate biosynthesis pathway showed that these observations are consistent with the in vivo cleavage of 5,10-methylene-THF by a side-activity of PanB, with FolK-mediated recycling of the pterin cleavage product, and with regulation of folate biosynthesis by folates or their damage products.
Contributors
Submitter of the first revision: Christopher Henry
Submitter of this revision: administrator
Modellers: administrator, Christopher Henry

Metadata information

is (2 statements)
BioModels Database MODEL1602280003
BioModels Database BIOMD0000000690

isDescribedBy (2 statements)
PubMed 27065985
PubMed 27065985

hasTaxon (1 statement)
Taxonomy Escherichia coli

hasProperty (1 statement)
hasPart (2 statements)

Curation status
Curated

Tags

Connected external resources

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Model files

BIOMD0000000690_url.xml SBML L2V4 representation of Thiaville2016 - Folate pathway model (PanB overexpression and THF regulation) 66.31 KB Preview | Download

Additional files

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BIOMD0000000690_urn.xml Auto-generated SBML file with URNs 66.30 KB Preview | Download
MODEL1602280003.cps Curated and annotated model COPASI file. 79.84 KB Preview | Download
MODEL1602280003.sedml SED-ML file for figure 7B of the reference publication. Parameter changes: FolA, 31,170 to 86,170 ; FolC, 6,184 to 10,000 ; FolK, 15.8 to 24.8 and FolP, 4,000 to 8,000. 4.99 KB Preview | Download

  • Model originally submitted by : Christopher Henry
  • Submitted: Feb 28, 2016 9:45:47 PM
  • Last Modified: Mar 13, 2018 5:14:53 PM
Revisions
  • Version: 3 public model Download this version
    • Submitted on: Mar 13, 2018 5:14:53 PM
    • Submitted by: administrator
    • With comment: Model name updated using online editor.
  • Version: 2 public model Download this version
    • Submitted on: May 31, 2017 11:42:28 AM
    • Submitted by: Christopher Henry
    • With comment: Current version of Thiaville2016 - Folate pathway model with induced PanB reaction and folate pathway
  • Version: 1 public model Download this version
    • Submitted on: Feb 28, 2016 9:45:47 PM
    • Submitted by: Christopher Henry
    • With comment: Original import of Henry2016 Folate pathway model with induced PanB reaction and folate pathway

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Legends
: Variable used inside SBML models


Species
Species Initial Concentration/Amount
AMP

AMP ; AMP
2.8E-4 mmol
Glycine

glycine ; Glycine
2.77E-4 mmol
p ABA

4-Aminobenzoate ; 4-aminobenzoate
1.0E-5 mmol
H2 HMPterinPP

6-(Hydroxymethyl)-7,8-dihydropterin ; phosphorylation ; dihydropterin
1.0E-5 mmol
PPi

Diphosphate
5.0E-4 mmol
L Glutamate

L-Glutamate ; glutamate(2-)
8.46E-4 mmol
DHF

Dihydrofolate ; dihydrofolate(2-)
1.0E-5 mmol
ATP

ATP ; ATP
0.0096 mmol
THF

tetrahydrofolate ; Tetrahydrofolate
1.69E-4 mmol
Reactions
Reactions Rate Parameters
ATP + H2_HMPt => AMP + H2_HMPterinPP compartment*k1*ATP*H2_HMPt k1=24.8
THF + L_serine => CH2_THF + Glycine compartment*(k1*THF*L_serine-k2*CH2_THF*Glycine) k1=4080.0; k2=2000.0
p_ABA + H2_HMPterinPP => PPi + H2_Pteroate compartment*k1*p_ABA*H2_HMPterinPP k1=8000.0
CH2_THF => H2_HMPt + p_ABA compartment*k1*CH2_THF k1=0.008
L_Glutamate + ATP + H2_Pteroate => DHF + ADP + Phosphate compartment*k1*L_Glutamate*ATP*H2_Pteroate k1=10029.0
DHF + NADPH => NADP + THF compartment*k1*DHF*NADPH k1=86170.0
Curator's comment:
(added: 20 Mar 2018, 22:04:29, updated: 20 Mar 2018, 22:04:29)
Attempt at reproducing figure 7B of the reference publication. Parameter values in table 3 of the supplementary material did not reproduce the results of the publication. To correct the steady state values of the metabolites in Fig 7B, reaction rate constants were changed: FolA, 31,170 to 86,170 ; FolC, 6184 to 10,000 ; FolK, 15.8 to 24.8 and FolP, 4000 to 8000. However the metabolites in the curated lower figure take at least 100 times longer to reach steady state than what is depicted in the reference publication. The significance of the results is lost by changing parameter values other than influx and PanB V_max. The reproducibility of the results may rely on the initial conditions of the metabolites.