Cyclase-Associated Protein Cap with Multiple Domains Contributes to Mycotoxin Biosynthesis and Fungal Virulence in Aspergillus flavus

Abstract

In Aspergillus, the cyclic adenosine monophosphate (cAMP) signaling modulates asexual development and mycotoxin biosynthesis. Here, we characterize the cyclase-associated protein Cap in the pathogenic fungus Aspergillus flauvs. The cap disruption mutant exhibited dramatic reduction in hyphal growth, conidiation, and spore germination, while an enhanced production of the sclerotia was observed in this mutant. Importantly, the cap gene was found to be important for mycotoxin biosynthesis and virulence. The domain deletion study demonstrated that each domain played an important role for the Cap protein in regulating cAMP/protein kinase A (PKA) signaling, while only P1 and CARP domains were essential for the full function of Cap. The phosphorylation of Cap at S35 was identified in A. flavus, which was found to play a negligible role for the function of Cap. Overall, our results indicated that Cap with multiple domains engages in mycotoxin production and fungal pathogenicity, which could be designed as potential control targets for preventing this fungal pathogen.

MAPK pathway‐related tyrosine phosphatases regulate development, secondary metabolism and pathogenicity in fungus Aspergillus flavus

“…To analyse AFs, 10 6 spores of each strain were cultured on YES liquid media at 29°C for 6 days, then AFs were extracted using a previously described protocol (Yang et al ., 2019a). A procedure of TLC was used to detect AF production with a solvent system (chloroform:acetone = 9:1), and the TLC plates were examined using a fluorescent detector with an excitation wavelength of 365 nm (Yang et al ., 2019b). The experiments were repeated three times.…”

Transcriptome Sequencing Revealed an Inhibitory Mechanism of Aspergillus flavus Asexual Development and Aflatoxin Metabolism by Soy-Fermenting Non-Aflatoxigenic Aspergillus

“…The AFB1 production in the culture medium was assayed after 3 days and after 9 days of incubation. Aflatoxins were then extracted according to a previously described method [ 44 ]. Briefly, 500 µL of culture medium were used for AF extraction with chloroform and thin-layer chromatography (TLC) was performed to analyze AFB1 production.…”

The Methyltransferase AflSet1 Is Involved in Fungal Morphogenesis, AFB1 Biosynthesis, and Virulence of Aspergillus flavus

“…The Aflset1 gene deletion strains were prepared according to the method of homologous recombination (Yang et al, 2019), and named as Aflset1. 1168 bp 5 -flanking region (with primer Aflset1-p1 and Aflset1-p2) and 889 bp 3 -flanking region (primer Aflset1-p3 and Aflset1-p4) of Aflset1 were amplified, and fused together with pyrG by using nesting primer Aflset1-p7 and Aflset1-p8 according to the strategy scheme shown in Figure 1A.…”