title: Functional Characterization of New Polyketide Synthase Genes Involved in Ochratoxin A Biosynthesis in Aspergillus Ochraceus fc-1.
abstract: 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.
authors.affiliation: Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. wanglq20082009@163.com.
authors.forename: Liuqing
authors.initials: L
authors.lastname: Wang
authors.affiliation: Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. wangyan062006@163.com.|Key Laboratory of Agro-products Processing, Ministry of Agriculture, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. wangyan062006@163.com.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. juwubawangqi@163.com.
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. liufei0823@yeah.net.
authors.forename: Fei
authors.initials: F
authors.lastname: Liu
authors.affiliation: Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. sjonnim@gmail.com.
authors.forename: Jonathan Nimal
authors.initials: JN
authors.lastname: Selvaraj
authors.affiliation: Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. ling_na@yeah.net.
authors.forename: Lingna
authors.initials: L
authors.lastname: Liu
authors.affiliation: Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. fgxing@163.com.|Key Laboratory of Agro-products Processing, Ministry of Agriculture, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. fgxing@163.com.
authors.forename: Fuguo
authors.initials: F
authors.lastname: Xing
authors.affiliation: Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. zhaoyueju@caas.cn.|Key Laboratory of Agro-products Processing, Ministry of Agriculture, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. zhaoyueju@caas.cn.
authors.forename: Yueju
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. zhoulu1982@sohu.com.|Key Laboratory of Agro-products Processing, Ministry of Agriculture, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. zhoulu1982@sohu.com.
authors.forename: Lu
authors.initials: L
authors.lastname: Zhou
authors.affiliation: Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. liuyang01@caas.cn.|Key Laboratory of Agro-products Processing, Ministry of Agriculture, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. liuyang01@caas.cn.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
mesh_terms: D000595:Amino Acid Sequence; D001235:Aspergillus ochraceus / Q000235:genetics* / Q000378:metabolism*; D018076:DNA, Complementary / Q000235:genetics; D004271:DNA, Fungal / Q000032:analysis; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D009793:Ochratoxins / Q000096:biosynthesis*; D010802:Phylogeny; D048630:Polyketide Synthases / Q000235:genetics*; D017422:Sequence Analysis, DNA; D003313:Zea mays / Q000382:microbiology
chemical_list: D018076:DNA, Complementary; D004271:DNA, Fungal; D009793:Ochratoxins; C025589:ochratoxin A; D048630:Polyketide Synthases
keywords: biosynthetic pathway; homologous recombination; ochratoxin A; polyketide synthase