Category:PK
From Metabolomics.JP
Polyketide (ポリケチド)
Contents |
Class Overview
Polyketides are synthesized through the polymerization of acetyl units (β-ketomethylene chain).
| 1st Class | ||
|---|---|---|
| PK4: Four C2 Units orsellinic acid, 6-methylsalicylic acid, triacetic acid lactone, asperlin, usnic acid, methylphloracetophenone, penicillic acid, patulin |
PK5: Five C2 Units citrinin, aflatoxin, augenone, sepedonin, stipitatonic acid |
PK6: Six C2 Units plumbagin, 7-methyljuglone, juglone, variotin |
| PK7: Seven and eight C2 Units Anthraquinone rings |
PK9: Nine C2 Units Tetracyclines | |
Polyketide Synthase (PKS)
| actinomycetes (bacteria) | fungi | |
|---|---|---|
| non-aromatic | Type I (non-iterative) |
Type II (iterative) |
| aromatic | Type II (iterative) |
Type II (iterative) |
Type I PKS (non-iterative)
- multi catalytic domains exist in a single protein
- chain length is determined by the number of catalytic domains
- products are non-aromatic (e.g. erythromycin, nigericin)
Ref. Erythromycin biosynthesis in Nat Prod Rep 18, 380 (2001)
Type II PKS (iterative)
- three proteins (KSalpha, KSbeta, ACP) are repeatedly used for carbon chain elongation
- chain length is determined by another protein, CLF
- products are aromatic (e.g. chiorotetracycline, pradimicin)
Non-ribosomal peptide synthase (NRPS)
vancomycin
PKS in Fungi
- both aromatic and non-aromatic compounds are generated by iterative PKS
- methyl branch is transferred from methionine, not methylmalonyl CoA
Ref. Dewick, PM Medicinal Natural Products (2009)
