Expression of a gfp gene in Penicillium nordicum under control of the promoter of the ochratoxin A polyketide synthase gene

Ochratoxine A (OTA), a potential human carcinogen is produced by several species of Aspergillus and Penicillium, including Aspergillus westerdijkiae. In this study a putative polyketide synthase gene aolc35-12 has been partially cloned from A. westerdijkiae. The predicted amino acid sequence of the 3.22 kb clone was found to have a high degree of similarity to other previously identified polyketide synthase genes from various OTA-producing fungi including Aspergillus ochraceus, Aspergillus niger, Aspergillus carbonarius and Penicillium nordicum. The aolc35-12 gene was disrupted and inactivated by insertion of Escherichia coli hygromycin B phosphotransferase gene, which resulted in an OTA negative mutant aoΔlc35-12. Genetic complementation confirmed aolc35-12 as OTA-polyketide synthase gene. Furthermore, study of the differential expression of aolc35-12 and a previously identified OTA-polyketide synthase gene, i.e. aoks1, in the wild-type A. westerdijkiae and aoΔlc35-12 mutant revealed that aolc35-12 could code for a certain polyketide compound complementary for the expression of aoks1 and hence for the activation of OTA biosynthesis system in A. westerdijkiae.

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Targeting a polyketide synthase gene for Aspergillus carbonarius quantification and ochratoxin A assessment in grapes using real-time PCR

International Journal of Food Microbiology ◽

10.1016/j.ijfoodmicro.2006.11.006 ◽

2007 ◽

Vol 115 (3) ◽

pp. 313-318 ◽

Cited By ~ 59

Author(s):

Ali Atoui ◽

Florence Mathieu ◽

Ahmed Lebrihi

Keyword(s):

Real Time ◽

Ochratoxin A ◽

Real Time Pcr ◽

Polyketide Synthase ◽

Aspergillus Carbonarius ◽

Polyketide Synthase Gene

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A polyketide synthase gene required for ochratoxin A biosynthesis in Aspergillus ochraceus

Microbiology ◽

10.1099/mic.0.26619-0 ◽

2003 ◽

Vol 149 (12) ◽

pp. 3485-3491 ◽

Cited By ~ 115

Author(s):

J. O'Callaghan ◽

M. X. Caddick ◽

A. D. W. Dobson

Keyword(s):

Ochratoxin A ◽

Polyketide Synthase ◽

Subtractive Hybridization ◽

Polyketide Synthases ◽

Aspergillus Ochraceus ◽

Predicted Amino Acid Sequence ◽

Acyl Transferase ◽

Reverse Transcription Pcr ◽

Polyketide Synthase Gene

Ochratoxin A is an important nephrotoxic and nephrocarcinogenic mycotoxin, produced by Aspergillus ochraceus as a polyketide-derived secondary metabolite. A portion of a putative polyketide synthase gene (pks) involved in the biosynthesis of this mycotoxin was cloned by using a suppression subtractive hybridization PCR-based approach. The predicted amino acid sequence of the 1·4 kb clone shared 28–35 % identity to acyl transferase regions from fungal polyketide synthases found in the databases. Based on reverse transcription PCR studies, the pks gene is expressed only under ochratoxin A permissive conditions and only during the early stages of the mycotoxin synthesis. A mutant in which the pks gene has been interrupted cannot synthesize ochratoxin A. This report is the first of the cloning and characterization of a gene involved in ochratoxin A biosynthesis.

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