Isochorismate synthase

{{Infobox enzyme

| Name = Isochorismate synthase

| EC_number = 5.4.4.2

| CAS_number = 37318-53-9

| GO_code =

| image = Isochorismate Synthase.png

| width =

| caption = Ishochorismate Synthase cartoon view (2 subunits)

}}

Isochorismate synthase ([http://www.chem.qmul.ac.uk/iubmb/enzyme/EC5/4/4/2.html] {{EnzExplorer|5.4.4.2}}) is an isomerase enzyme that catalyzes the first step in the biosynthesis of vitamin K₂ (menaquinone) in Escherichia coli.{{cite journal | vauthors = Daruwala R, Bhattacharyya DK, Kwon O, Meganathan R | title = Menaquinone (vitamin K2) biosynthesis: overexpression, purification, and characterization of a new isochorismate synthase from Escherichia coli | journal = Journal of Bacteriology | volume = 179 | issue = 10 | pages = 3133–8 | date = May 1997 | pmid = 9150206 | pmc = 179089 | doi = 10.1128/jb.179.10.3133-3138.1997}}

Reaction

Isochorismate synthase, belongs to the isomerase enzyme family. More specifically it is classified as an intramolecular transferase because it transfers the hydroxy group of chorismate between carbons.{{cite web|title=EC 5.4.4.2|url=http://www.chem.qmul.ac.uk/iubmb/enzyme/reaction/misc/shikim.html|access-date=30 November 2014|publisher=IUBMB}}

Isochorismate synthase catalyzes the irreversible conversion of chorismate to isochorismate:

File:Isochorismate Synthase Rxn.png

Isochorismate synthase is most active at 37 °C and at a pH between 7.5 and 8. It requires Mg²⁺ as a cofactor, in a concentration between 100 μM and 1 mM. 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{{cite journal | vauthors = Payne RJ, Bulloch EM, Toscano MM, Jones MA, Kerbarh O, Abell C | title = Synthesis and evaluation of 2,5-dihydrochorismate analogues as inhibitors of the chorismate-utilising enzymes | journal = Organic & Biomolecular Chemistry | volume = 7 | issue = 11 | pages = 2421–9 | date = June 2009 | pmid = 19462053 | doi = 10.1039/B901694E | url = https://pubs.rsc.org/en/Content/ArticleLanding/2009/OB/b901694e }}
Cu²⁺
Hg²⁺
K⁺
Mg²⁺ at concentrations above 1 mM
N-ethylmaleimide

Nomenclature

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

Pathways

Image:5jzd.jpg

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 enterobactin pathway in Escherichia coli. This enzyme catalyzes the first step in the biosynthesis of salicylic acid in Pseudomonas aeruginosa.{{Cite journal|url = http://www.jbc.org/content/278/19/16893.full|title = Isochorismate Synthase (PchA), the First and Rate-limiting Enzyme in Salicylate Biosynthesis of Pseudomonas aeruginosa|last = Gaille|date = May 9, 2003|journal = The Journal of Biological Chemistry| volume=278 | issue=19 | pages=16893–16898 | doi=10.1074/jbc.M212324200 | doi-access=free }}

Isochorismate synthase has several other homologs that are found in other organisms. These include:

Enzyme Genes/Enzyme Names	Organisms
class="wikitable"
ICS	*Arabidopsis thaliana Cyanidium caldarium Glycine max Nicotiana benthamiana Populus fremontil Populus angustifolia Populus 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

References

Category:EC 5.4.4