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Open AccessArticle

Functional Characterization of New Polyketide Synthase Genes Involved in Ochratoxin A Biosynthesis in Aspergillus Ochraceus fc-1

1
Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China
2
Key Laboratory of Agro-products Processing, Ministry of Agriculture, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China
*
Author to whom correspondence should be addressed.
These authors contributed equally to this work.
Academic Editor: Jiujiang Yu
Toxins 2015, 7(8), 2723-2738; https://doi.org/10.3390/toxins7082723
Received: 26 June 2015 / Revised: 10 July 2015 / Accepted: 17 July 2015 / Published: 24 July 2015
Ochratoxin A (OTA), a potentially carcinogenic mycotoxin which contaminates grains, is produced by several Aspergillus species. A comparative sequence analysis of the OTA-producing Aspergillus ochraceus fc-1 strain and other Aspergillus species was performed. Two new OTA-related polyketide synthase (PKS) (AoOTApks) genes were identified. The predicted amino acid sequence of AoOTApks-1 displayed high similarity to previously identified PKSs from OTA-producing A. carbonarius ITEM 5010 (67%; [PI] No. 173482) and A. niger CBS 513.88 (62%; XP_001397313). However, the predicted amino acid sequence of AoOTApks-2 displayed lower homology with A. niger CBS 513.88 (38%) and A. carbonarius ITEM 5010 (28%). A phylogenetic analysis of the β-ketosynthase and acyl-transferase domains of the AoOTApks proteins indicated that they shared a common origin with other OTA-producing species, such as A. carbonarius, A. niger, and A. westerdijkiae. A real-time reverse-transcription PCR analysis showed that the expression of AoOTApks-1 and -2 was positively correlated with the OTA concentration. The pks gene deleted mutants ∆AoOTApks-1 and ∆AoOTApks-2 produced nil and lesser OTA than the wild-type strain, respectively. Our study suggests that AoOTApks-1 could be involved in OTA biosynthesis, while AoOTApks-2 might be indirectly involved in OTA production. View Full-Text
Keywords: ochratoxin A; polyketide synthase; homologous recombination; biosynthetic pathway ochratoxin A; polyketide synthase; homologous recombination; biosynthetic pathway
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MDPI and ACS Style

Wang, L.; Wang, Y.; Wang, Q.; Liu, F.; Selvaraj, J.N.; Liu, L.; Xing, F.; Zhao, Y.; Zhou, L.; Liu, Y. Functional Characterization of New Polyketide Synthase Genes Involved in Ochratoxin A Biosynthesis in Aspergillus Ochraceus fc-1. Toxins 2015, 7, 2723-2738.

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