Escherichia coli K-12 substr. MG1655 Enzyme: dihydroneopterin triphosphate 2'-epimerase

Gene: folX Accession Numbers: G7195 (EcoCyc), b2303, ECK2297

Regulation Summary Diagram: ?

Regulation summary diagram for folX

Subunit composition of dihydroneopterin triphosphate 2'-epimerase = [FolX]8
         dihydroneopterin triphosphate 2'-epimerase monomer = FolX

Dihydroneopterin triphosphate 2'-epimerase (FolX) has been known in E. coli for some time. FolX is required for tetrahydromonapterin biosynthesis. The epimerase reaction yields dihydromonapterin triphosphate, from which tetrahydromonapterin is produced after successive dephosphorylation and oxidation [Pribat10]. Tetrahydromonapterin is the major pterin in E. coli [Ikemoto02].

A crystal structure of FolX has been solved at 2.9 Å resolution. Two tetramers associate head-to-head to form the active enzyme complex [Ploom99].

A folX deletion mutant shows no detectable growth defect on complete and minimal medium [Haussmann98]. E. coli normally excretes a form of monapterin into the medium [Wachter80]; the extracellular monapterin is lost in a folX mutant, while the folate profile of the cells remains the same as in wild type [Pribat10]. Disruption of either folX or folM leads to decreased sensitivity to the antibiotics trimethoprim and slufamonomethoxine [Girgis09].

Review: [Bermingham02]

Gene Citations: [Zaslaver06]

Locations: cytosol

Map Position: [2,419,347 -> 2,419,709] (52.14 centisomes, 188°)
Length: 363 bp / 120 aa

Molecular Weight of Polypeptide: 14.082 kD (from nucleotide sequence), 14.0 kD (experimental) [Haussmann98 ]

Molecular Weight of Multimer: 100.0 kD (experimental) [Haussmann98]

Unification Links: ASAP:ABE-0007603 , DIP:DIP-9679N , EchoBASE:EB4011 , EcoGene:EG14263 , EcoliWiki:b2303 , OU-Microarray:b2303 , PortEco:folX , PR:PRO_000022683 , Pride:P0AC19 , Protein Model Portal:P0AC19 , RefSeq:NP_416806 , RegulonDB:G7195 , SMR:P0AC19 , String:511145.b2303 , UniProt:P0AC19

Relationship Links: InterPro:IN-FAMILY:IPR006157 , PDB:Structure:1B9L , Pfam:IN-FAMILY:PF02152 , Smart:IN-FAMILY:SM00905

In Paralogous Gene Group: 406 (2 members)

Gene-Reaction Schematic: ?

Gene-Reaction Schematic

Genetic Regulation Schematic: ?

Genetic regulation schematic for folX

GO Terms:

Biological Process: GO:0006760 - folic acid-containing compound metabolic process Inferred from experiment Inferred by computational analysis [GOA01a, Pribat10]
Molecular Function: GO:0008719 - dihydroneopterin triphosphate 2'-epimerase activity Inferred from experiment [Haussmann98]
GO:0004150 - dihydroneopterin aldolase activity Inferred by computational analysis [GOA01a]
GO:0016853 - isomerase activity Inferred by computational analysis [UniProtGOA11]
Cellular Component: GO:0005829 - cytosol Inferred from experiment Inferred by computational analysis [DiazMejia09, Ishihama08]

MultiFun Terms: metabolism central intermediary metabolism unassigned reversible reactions

Essentiality data for folX knockouts: ?

Growth Medium Growth? T (°C) O2 pH Osm/L Growth Observations
LB enriched Yes 37 Aerobic 6.95   Yes [Gerdes03, Comment 1]
LB Lennox Yes 37 Aerobic 7   Yes [Baba06, Comment 2]
M9 medium with 1% glycerol Yes 37 Aerobic 7.2 0.35 Yes [Joyce06, Comment 3]
MOPS medium with 0.4% glucose Yes 37 Aerobic 7.2 0.22 Yes [Baba06, Comment 2]
Yes [Feist07, Comment 4]

Last-Curated ? 18-Nov-2009 by Keseler I , SRI International

Enzymatic reaction of: dihydroneopterin triphosphate 2'-epimerase

Synonyms: H2NTP epimerase, D-erythro-dihydroneopterin triphosphate 2'-epimerase, D-erythro-7,8-dihydroneopterin triphosphate epimerase

EC Number: 5.1.99.-

7,8-dihydroneopterin 3'-triphosphate <=> 7,8-dihydromonapterin triphosphate

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction of enzyme catalysis.

This reaction is reversible. [Haussmann98]

In Pathways: tetrahydromonapterin biosynthesis

Partial [Heine75] and full [Ahn97, Haussmann97] purification of the enzyme was first reported from E. coli B.

Based on steady-state kinetic parameters, the equilibrium constant for the reaction was estimated to be 0.77 [Haussmann98].

Cofactors or Prosthetic Groups [Comment 5]: Mg2+ [Heine75]

Alternative Cofactors for Mg2+ [Comment 5 ]: Mn2+ , Ca2+

Kinetic Parameters:

Km (μM)
7,8-dihydroneopterin 3'-triphosphate

T(opt): 55 °C [Haussmann98]

pH(opt): 5.8-6.2 [Heine75]

Sequence Features

Protein sequence of dihydroneopterin triphosphate 2'-epimerase monomer with features indicated

Feature Class Location Citations Comment
Cleavage-of-Initial-Methionine 1
[Haussmann95, Ahn97, UniProt12a]
UniProt: Removed.
Chain 2 -> 120
UniProt: D-erythro-7,8-dihydroneopterin triphosphate epimerase;
Sequence-Conflict 27 -> 30
[Ahn97, UniProt10a]
UniProt: (in Ref. 2; AAB47972);
Sequence-Conflict 48 -> 49
[Ahn97, UniProt10a]
UniProt: (in Ref. 2; AAB47972);
Sequence-Conflict 55
[Ahn97, UniProt10a]
UniProt: (in Ref. 2; AAB47972);
Sequence-Conflict 107
[Ahn97, UniProt10a]
UniProt: (in Ref. 2; AAB47972);

Gene Local Context (not to scale): ?

Gene local context diagram

Transcription Unit:

Transcription-unit diagram


Markus Krummenacker on Tue Oct 14, 1997:
Gene object created from Blattner lab Genbank (v. M52) entry.


Ahn97: Ahn C, Byun J, Yim J (1997). "Purification, cloning, and functional expression of dihydroneopterin triphosphate 2'-epimerase from Escherichia coli." J Biol Chem 1997;272(24);15323-8. PMID: 9182560

Baba06: Baba T, Ara T, Hasegawa M, Takai Y, Okumura Y, Baba M, Datsenko KA, Tomita M, Wanner BL, Mori H (2006). "Construction of Escherichia coli K-12 in-frame, single-gene knockout mutants: the Keio collection." Mol Syst Biol 2;2006.0008. PMID: 16738554

Bermingham02: Bermingham A, Derrick JP (2002). "The folic acid biosynthesis pathway in bacteria: evaluation of potential for antibacterial drug discovery." Bioessays 24(7);637-48. PMID: 12111724

DiazMejia09: Diaz-Mejia JJ, Babu M, Emili A (2009). "Computational and experimental approaches to chart the Escherichia coli cell-envelope-associated proteome and interactome." FEMS Microbiol Rev 33(1);66-97. PMID: 19054114

Feist07: Feist AM, Henry CS, Reed JL, Krummenacker M, Joyce AR, Karp PD, Broadbelt LJ, Hatzimanikatis V, Palsson BO (2007). "A genome-scale metabolic reconstruction for Escherichia coli K-12 MG1655 that accounts for 1260 ORFs and thermodynamic information." Mol Syst Biol 3;121. PMID: 17593909

Gerdes03: Gerdes SY, Scholle MD, Campbell JW, Balazsi G, Ravasz E, Daugherty MD, Somera AL, Kyrpides NC, Anderson I, Gelfand MS, Bhattacharya A, Kapatral V, D'Souza M, Baev MV, Grechkin Y, Mseeh F, Fonstein MY, Overbeek R, Barabasi AL, Oltvai ZN, Osterman AL (2003). "Experimental determination and system level analysis of essential genes in Escherichia coli MG1655." J Bacteriol 185(19);5673-84. PMID: 13129938

Girgis09: Girgis HS, Hottes AK, Tavazoie S (2009). "Genetic architecture of intrinsic antibiotic susceptibility." PLoS One 4(5);e5629. PMID: 19462005

GOA01a: GOA, DDB, FB, MGI, ZFIN (2001). "Gene Ontology annotation through association of InterPro records with GO terms."

Haussmann95: Haussmann C., Bacher A. (1995). Data submission to UniProtKB on 1995-05.

Haussmann97: Haussmann C, Rohdich F, Lottspeich F, Eberhardt S, Scheuring J, Mackamul S, Bacher A (1997). "Dihydroneopterin triphosphate epimerase of Escherichia coli: purification, genetic cloning, and expression." J Bacteriol 1997;179(3);949-51. PMID: 9006053

Haussmann98: Haussmann C, Rohdich F, Schmidt E, Bacher A, Richter G (1998). "Biosynthesis of pteridines in Escherichia coli. Structural and mechanistic similarity of dihydroneopterin-triphosphate epimerase and dihydroneopterin aldolase." J Biol Chem 273(28);17418-24. PMID: 9651328

Heine75: Heine MC, Brown GM (1975). "Enzymatic epimerization of D-erythro-dihydroneopterin triphosphate to L-threo-dihydroneopterin triphosphate." Biochim Biophys Acta 1975;411(2);236-49. PMID: 1103974

Ikemoto02: Ikemoto K, Sugimoto T, Murata S, Tazawa M, Nomura T, Ichinose H, Nagatsu T (2002). "(6R)-5,6,7,8-tetrahydro-L-monapterin from Escherichia coli, a novel natural unconjugated tetrahydropterin." Biol Chem 383(2);325-30. PMID: 11934271

Ishihama08: Ishihama Y, Schmidt T, Rappsilber J, Mann M, Hartl FU, Kerner MJ, Frishman D (2008). "Protein abundance profiling of the Escherichia coli cytosol." BMC Genomics 9;102. PMID: 18304323

Joyce06: Joyce AR, Reed JL, White A, Edwards R, Osterman A, Baba T, Mori H, Lesely SA, Palsson BO, Agarwalla S (2006). "Experimental and computational assessment of conditionally essential genes in Escherichia coli." J Bacteriol 188(23);8259-71. PMID: 17012394

Ploom99: Ploom T, Haussmann C, Hof P, Steinbacher S, Bacher A, Richardson J, Huber R (1999). "Crystal structure of 7,8-dihydroneopterin triphosphate epimerase." Structure Fold Des 1999;7(5);509-16. PMID: 10378270

Pribat10: Pribat A, Blaby IK, Lara-Nunez A, Gregory JF, de Crecy-Lagard V, Hanson AD (2010). "FolX and FolM Are Essential for Tetrahydromonapterin Synthesis in Escherichia coli and Pseudomonas aeruginosa." J Bacteriol 192(2):475-82. PMID: 19897652

UniProt09: UniProt Consortium (2009). "UniProt version 15.8 released on 2009-10-01 00:00:00." Database.

UniProt10a: UniProt Consortium (2010). "UniProt version 2010-11 released on 2010-11-02 00:00:00." Database.

UniProt12a: UniProt Consortium (2012). "UniProt version 2012-02 released on 2012-02-29 00:00:00." Database.

UniProtGOA11: UniProt-GOA (2011). "Gene Ontology annotation based on manual assignment of UniProtKB keywords in UniProtKB/Swiss-Prot entries."

Wachter80: Wachter H, Hausen A, Reider E, Schweiger M (1980). "Pteridine excretion from cells as indicator of cell proliferation." Naturwissenschaften 67(12);610-1. PMID: 7015154

Zaslaver06: Zaslaver A, Bren A, Ronen M, Itzkovitz S, Kikoin I, Shavit S, Liebermeister W, Surette MG, Alon U (2006). "A comprehensive library of fluorescent transcriptional reporters for Escherichia coli." Nat Methods 3(8);623-8. PMID: 16862137

Other References Related to Gene Regulation

Durand10: Durand S, Storz G (2010). "Reprogramming of anaerobic metabolism by the FnrS small RNA." Mol Microbiol 75(5);1215-31. PMID: 20070527

Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of EcoCyc: Nucleic Acids Research 41:D605-12 2013
Page generated by SRI International Pathway Tools version 19.0 on Tue Oct 13, 2015, BIOCYC14A.