Characterization and abolishment of the cyclopiazonic acids produced by Aspergillus oryzae HMP-F28
2018
Cao, Ting | Ling, Junhong | Liu, Yi | Chen, Xiaoqi | Tian, Xiaoyue | Meng, Dali | Pan, Huaqi | Hu, Jiangchun | Wang, Nan
Extracellular alkalinization and H₂O₂ production are important early events during induced resistance establishment in plants. In a screen for metabolites as plant resistance activators from 98 fungal isolates associated with marine sponge Hymeniacidon perleve, the cyclopiazonic acids (CPAs) produced by Aspergillus oryzae HMP-F28 induced significant extracellular alkalinization coupled with augmented H₂O₂ production in tobacco cell suspensions. Bioassay-guided fractionation led to the isolation and structural elucidation of a new CPA congener (4, 3-hydroxysperadine A) and three known ones (1–3). To construct a mutasynthetic strain to generate unnatural CPA analogues, a hybrid pks-nrps gene (cpaS) was disrupted to abolish the production of the critical precursor of cyclo-acetoacetyl-L-tryptophan (cAATrp) and all the downstream CPA products. Elimination of cAATrp will allow cAATrp mimics being processed by the CPA biosynthetic machinery to produce CPA derivatives with designed structural features.
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