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Isochorismate Synthase

Isochorismate synthase (MenF) (EC number 5.4.4.2) is involved in the biosynthesis of vitamin K in Escherichia coli. This enzyme catalyzes the first step in the biosynthesis of menaquinone (vitamin K).[1]

Ishochorismate Synthase cartoon view (2 subunits)
Identifiers -
EC number 5.4.4.2
CAS number 37318-53-9
Databases -
IntEnz IntEnz view
BRENDA BRENDA entry
ExPASy NiceZime view
KEGG KEGG entry
MetaCyc metabolic pathway
PRIAM profile
PDB 2EUA
Gene Ontology EGO

Reaction

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Isochorismate synthase is an enzyme that catalyzes the irreversible reaction:

Chorismate Isochorismate

The only subrate of this reaction is chorismate, and the product is isochorismate. Isochorismate synthase is most active at 37℃ and at a pH between 7.5-8. Isochorismate synthase requires Mg2+. The concentration of Mg2+ may range from 100μM-1mM.[1] Inhibitors of isochorismate synthase include:

  • (4R,5R)-4-hydroxy-5-(1-carboxyvinyloxy)-cyclohex-1-ene carboxylate
  • (4R,5R)-4-hydroxy-5-carboxymethoxy-cyclohex-1-enecarboxylate
  • (4R,5R)-5-(2-carboxy-allyloxy)-4-hydroxy-cyclohex-1-enecarboxylate
  • (4R,5R,6S)-6-ammonio-5-[(1-carboxylatoethenyl)oxy]-4-hydroxycyclohex-1-ene-1-carboxylate
  • (4R,5R,7R)-5-(1-carboxy-ethoxy)-4-hydroxy-cyclohex-1-enecarboxylate
  • (4R,5R,7S)-5-(1-carboxy-ethoxy)-4-hydroxy-cyclohex-1-enecarboxylate
  • (4R,5S,6S)-4-ammonio-5-[(1-carboxylatoethenyl)oxy]-6-hydroxycyclohex-1-ene-1-carboxylate
  • (4R,5S,6S)-5-[(1-carboxylatoethenyl)oxy]-4,6-dihydroxycyclohex-1-ene-1-carboxylate[2]
  • Cu2+
  • Hg2+
  • K+
  • Mg2+ at concentrations above 1mM
  • NEM

Nomenclature

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Isochorismate synthase, or MenF, belongs to the isomerase enzyme family. More specifically it is classified as an intermolecular transferase because it transfers the hydroxy group of chorismate between carbons.[3] The systematic name of this enzyme is isochorismate hydroxymutase, and the common name is isochorismate synthase. Other names for this enzyme include:

  • Isochorismate mutase
  • Menaquinone-specific isochorismate synthase
  • MenF

Vitamin K

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Vitamin K is a quinone, which means it is a ring compound that participates in redox reactions. These redox reactions take place in various organisms ranging from plants where electrons are transferred during photosynthesis, humans where electrons are transferred to modify certain types of proteins, and even in bacteria where electrons are transferred during anaerobic respiration.[4]

Pathways

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MenF is a gene that codes for the isochorismate synthase found in the menaquinone pathway in Escherichia coli, not to be mistaken for the entC gene that codes for the isochorismate synthase found in the enterobacter pathway in Escherichia coli.[1] Isochorismate synthase has several other homologs that are found in other organisms. These include:

Enzyme Genes/Enzyme Names Organisms
ICS Arabidopsis thaliana

Cyanidium caldarium

Glycime max

Nicotiana benthamiana

Populus fremontil

Populus angustifolia

Populous tremuloides

ICS1 Arabidopsis thaliana
ICS1 gene product Arabidopsis thaliana

Cyanidium caldarium

ICS2 Arabidopsis thaliana
Isochorismate synthase Arabidopsis thaliana

Cyanidium caldarium

Glycine max

Isochorismate synthase 1 Arapidopsis thaliana
Mbtl Mycobacterium tuberculosis
PchA Pseudomonas aeruginosa

Sources

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  1. ^ a b c Daruwala, R; Bhattacharyya, D K; Kwon, O; Meganathan, R (May 1997). "Menaquinone (vitamin K2) biosynthesis: overexpression, purification, and characterization of a new isochorismate synthase from Escherichia coli". Journal of Microbiology. 179: 3133–3138. PMID 179(10):3133-8. Retrieved 30 November 2014. {{cite journal}}: Check |pmid= value (help)
  2. ^ Payne, RJ; Bulloch, EM; Toscano, MM; Jones, MA; Kerbarh, O; Abell, C (2 April 2009). "Synthesis and evaluation of 2,5-dihydrochorismate analogues as inhibitors of the chorismate-utilising enzyme". Organic and Biomolecular Chemistry (11): 2421–2429. doi:10.1039/B901694E. PMID 19462053. Retrieved 30 November 2014.
  3. ^ "EC 5.4.4.2". IUBMB. Retrieved 30 November 2014.
  4. ^ van Oostende, C; Wildhalm, JR; Furt, F; Ducluzeau, AL; Basset, GJC (2011). "Phylloquinone (Vitamin K2): function,enzymes and genes". Advances in Botanical Research: 229–61. {{cite journal}}: |access-date= requires |url= (help)