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MetaCyc Enzyme: phytoene desaturase

Gene: crtIa Accession Number: G-12649 (MetaCyc)

Synonyms: carA2

Species: Myxococcus xanthus

Summary:
The bacterium Myxococcus xanthus produces the carotenoid all-trans-lycopene. Unlike organisms such as Pantoea ananatis, where a single enzyme, CrtI, catalyzes the isomerization of as well as all four desaturation steps required to convertFRAME: PHYTOENE| to all-trans-lycopene, in Myxococcus xanthus the process is catalyzed by two different enzymes. While CrtIa catalyzes the isomerization of 15-cis-phytoene as well as the first two desaturation steps, CrtIb catalyzes the two desaturation steps from all-trans-ζ-carotene to all-trans-lycopene.

The crtIa gene was found in a cluster of structural and regulatory genes associated with light-induced carotenogenesis, and was defined as a phytoene desaturase based on its similarity to such enzymes from from fungi and noncyanobacterial bacteria, as well as the crtIb gene from the same organism [Botella95]. A mutant with a transposon insertion in crtIa is unable to produce colored carotenoids, indicating an early role in carotenogenesis. Analysis of a carotene precursor accumulated by the mutant identified it as 15-cis-phytoene, suggesting that the enzyme is also responsible for its cis-trans isomerization to all-trans-phytoene [Iniesta07]. When the gene was introduced to an Escherichia coli strain able to produce 15-cis-phytoene, the absorption spectra of extracts of the organism showed the presence of all-trans-phytoene, all-trans phytofluene and all-trans-ζ-carotene, at decreasing concentrations, indicating that the enzyme is able to carry out desaturation steps up to the latter [Iniesta07].

Molecular Weight of Polypeptide: 57.784 kD (from nucleotide sequence)

Unification Links: Entrez-Nucleotide:Z21955 , Protein Model Portal:P54979 , UniProt:P54979

Relationship Links: InterPro:IN-FAMILY:IPR002937 , InterPro:IN-FAMILY:IPR008150 , InterPro:IN-FAMILY:IPR014105 , Panther:IN-FAMILY:PTHR10668:SF3 , Pfam:IN-FAMILY:PF01593 , Prosite:IN-FAMILY:PS00982

Gene-Reaction Schematic: ?

Credits:
Created 21-Mar-2011 by Caspi R , SRI International


Enzymatic reaction of: phytoene desaturase (ζ-carotene-forming)

EC Number: 1.3.99.29

15-cis-phytoene + 2 an oxidized electron acceptor <=> all-trans-ζ-carotene + 2 a reduced electron acceptor

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

Reversibility of this reaction is unspecified.

In Pathways: trans-lycopene biosynthesis I (bacteria)


Enzymatic reaction of: all-trans-phytoene desaturase

15-cis-phytoene + an oxidized electron acceptor <=> all-trans phytofluene + a reduced electron acceptor

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.

The reaction is favored in the direction shown.

In Pathways: trans-lycopene biosynthesis I (bacteria)


Enzymatic reaction of: phytofluene desaturase (phytoene desaturase)

all-trans phytofluene + an oxidized electron acceptor <=> all-trans-ζ-carotene + a reduced electron acceptor

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.

The reaction is favored in the direction shown.

In Pathways: trans-lycopene biosynthesis I (bacteria)

Cofactors or Prosthetic Groups: FAD


References

Botella95: Botella JA, Murillo FJ, Ruiz-Vazquez R (1995). "A cluster of structural and regulatory genes for light-induced carotenogenesis in Myxococcus xanthus." Eur J Biochem 233(1);238-48. PMID: 7588751

Iniesta07: Iniesta AA, Cervantes M, Murillo FJ (2007). "Cooperation of two carotene desaturases in the production of lycopene in Myxococcus xanthus." FEBS J 274(16);4306-14. PMID: 17662111


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 Sun Nov 23, 2014, BIOCYC13B.