Cloning and characterization of novel methylsalicylic acid synthase gene involved in the biosynthesis of isoasperlactone and asperlactone in Aspergillus westerdijkiae

• Published in: Fungal genetics and biology Vol. 46; no. 10; pp. 742 - 749
• Main Authors: Bacha, Nafees, Dao, Huy Phong, Atoui, Ali, Mathieu, Florence, O’Callaghan, John, Puel, Olivier, Liboz, Thierry, Dobson, Alan D.W., Lebrihi, Ahmed
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-10-2009; Elsevier
• Subjects: 6-Methylsalicylic acid; Acyltransferases - genetics; Acyltransferases - metabolism; Amino Acid Sequence; Aspergillus; Aspergillus - enzymology; Aspergillus - genetics; Aspergillus westerdijkiae; Asperlactone; Byssochlamys - enzymology; Byssochlamys - genetics; Byssochlamys nivea; Chemical engineering; Chemical Sciences; Cloning, Molecular; DNA, Fungal - chemistry; DNA, Fungal - genetics; Fungal Proteins - genetics; Fungal Proteins - metabolism; Gene Knockout Techniques; Genetic Complementation Test; Isoasperlactone; Life Sciences; Ligases - genetics; Ligases - metabolism; Macrolides - metabolism; Microbiology and Parasitology; Molecular Sequence Data; Molecular Structure; Multienzyme Complexes - genetics; Multienzyme Complexes - metabolism; Oxidoreductases - genetics; Oxidoreductases - metabolism; Polyketide synthase; Sequence Analysis, DNA; Sequence Homology, Amino Acid; Streptomyces - enzymology; Streptomyces - genetics; Streptomyces viridochromogenes; Toxicology; Vegetal toxicology and mycotoxicology; Polyketide synthase; Aspergillus westerdijkiae; Asperlactone; Isoasperlactone; 6-Methylsalicylic acid; ISOASPERLACTONE; 6-Methylsalicylicacid; 6-METHYLSALICYLIC ACID; POLYKETIDE SYNTHASE; ASPERLACTONE; ASPERGILLUS WESTERDIJKIAE
• ISSN: 1087-1845; 1096-0937
• DOI: 10.1016/j.fgb.2009.07.002

Aspergillus westerdijkiae is the main producer of several biologically active polyketide metabolites including isoasperlactone and asperlactone. A 5298
bp polyketide synthase gene “
aomsas” has been cloned in
Aspergillus westerdijkiae by using gene walking approach and RACE-PCR. The predicted amino acid sequence of
aomsas shows an identity of 40–56% with different methylsalicylic acid synthase genes found in
Byssochlamys nivea,
P. patulum,
A. terreus and
Streptomyces viridochromogenes. Based on the reverse transcription PCR and kinetic secondary metabolites production studies,
aomsas expression was found to be associated with the biosynthesis of isoasperlactone and asperlactone. Moreover an
aomsas knockout mutant “
aoΔmsas” of
A. westerdijkiae, not only lost the capacity to produce isoasperlactone and asperlactone, but also 6-methylsalicylic acid. The genetically complemented mutant
ao+msas restored the biosynthesis of all the missing metabolites. Chemical complementation through the addition of 6-methylsalicylic acid, aspyrone and diepoxide to growing culture of
aoΔmsas mutant revealed that these compounds play intermediate roles in the biosynthesis of asperlactone and isoasperlactone.