Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
twitter

MetaCyc Enzyme: isoprene synthase

Gene: IspS Accession Number: G-11347 (MetaCyc)

Synonyms: isoprene synthase

Species: Populus alba

Summary:
Isoprene synthase is the final enzyme in the isoprene biosynthesis pathway. As such, it is a key regulator of isoprene emissions from plants (rev in [Sharkey08a]).

This enzyme has a transit peptide that is capable of targeting GFP to chloroplasts, suggesting that the native enzyme is present in that organelle [Sasaki05]. When a truncated form of isoprene synthase lacking the transit peptide is expressed in vitro it synthesizes isoprene [Sasaki05]. The Km of the enzyme for DMAPP is quite high, but the value is similar for an isoprene synthase studied in P.tremuloides [Silver95]. Both enzymes appear to be Mg2+-dependent, but this enzyme can also show reduced activity (~20-30%) with Mn2+ and Co2+ in vitro [Sasaki05].

IspS transcript levels are up-regulated in response to both heat (40 deg C) and continuous light whereas they are down-regulated in the dark [Sasaki05]. Not surprisingly based on its expression pattern, this enzyme has a relatively high temperature optimum [Sasaki05]. In addition, this gene appears to expressed at much higher levels in leaves than in stems and roots in accordance with the observed isoprene emission from leaves [Sasaki05].

Unification Links: Entrez-Nucleotide:AB198180 , Entrez:BAD98243 , Protein Model Portal:Q50L36 , UniProt:Q50L36

Relationship Links: InterPro:IN-FAMILY:IPR001906 , InterPro:IN-FAMILY:IPR005630 , InterPro:IN-FAMILY:IPR008930 , InterPro:IN-FAMILY:IPR008949 , Pfam:IN-FAMILY:PF01397 , Pfam:IN-FAMILY:PF03936

Gene-Reaction Schematic: ?

Gene Class: UNCLASSIFIED

Credits:
Created 05-Jun-2009 by Dreher KA , TAIR


Enzymatic reaction of: isoprene synthase

EC Number: 4.2.3.27

dimethylallyl diphosphate <=> isoprene + diphosphate

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

The reaction is favored in the direction shown.

In Pathways: isoprene biosynthesis I , isoprene biosynthesis II (engineered)

Cofactors or Prosthetic Groups: Mg2+ [Sasaki05]

Kinetic Parameters:

Substrate
Km (μM)
Citations
dimethylallyl diphosphate
8700.0
[Sasaki05]

T(opt): 40 °C [Sasaki05]

pH(opt): 8.0 [Sasaki05]


References

Sasaki05: Sasaki K, Ohara K, Yazaki K (2005). "Gene expression and characterization of isoprene synthase from Populus alba." FEBS Lett 579(11);2514-8. PMID: 15848197

Sharkey08a: Sharkey TD, Wiberley AE, Donohue AR (2008). "Isoprene emission from plants: why and how." Ann Bot (Lond) 101(1);5-18. PMID: 17921528

Silver95: Silver GM, Fall R (1995). "Characterization of aspen isoprene synthase, an enzyme responsible for leaf isoprene emission to the atmosphere." J Biol Chem 270(22);13010-6. PMID: 7768893


Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by SRI International Pathway Tools version 18.5 on Tue Nov 25, 2014, biocyc14.