Abstract
Accumulation of two benzoyl esters in Aspergillus ustus after feeding with alcohols was reported 30 years ago. To the best of our knowledge, the biosynthesis for these esters has not been elucidated prior to this study. Here, we demonstrate that these compounds are artifical products of the phenethyl polyketide ustethylin A biosynthestic pathway. In addition, four aditional benzoyl esters with different methylation levels were also isolated and identified as shunt products. Feeding experiments provided evidence that the enzyme-bound polyketide acyl intermediates are hijacked by externally fed MeOH or EtOH, leading to the formation of the benzoyl esters.Graphic abstract
Highlights
Secondary metabolites play an important role in ecological fitness of microorganisms, such as for protection from UV damage, toxic natural products and other microorganisms (Keller 2019)
1.5 mL (3%, v/v) of MeOH, EtOH or CD3OD were added into the three day-old A. ustus cultures in 250 mL flask containing 50 mL PDB medium, which were further maintained at 230 rpm and 30 °C for five days. 1 mL culture was extracted with EtOAc for LC–MS analysis
The aryl acids involved in the biosynthesis of ustethylins are the acyl components of the previously identified esters (De Jesus et al 1987) (Fig. 1b)
Summary
Secondary metabolites play an important role in ecological fitness of microorganisms, such as for protection from UV damage, toxic natural products and other microorganisms (Keller 2019). Polyketides with diverse biological and pharmacological activities are the most abundant fungal natural products (Keller et al 2005; Ran and Li 2020) These compounds are biosynthesized by the well-studied multidomain proteins—polyketide synthases (PKSs). We elucidated the first biosynthetic pathway of fungal phenethyl derivatives, i.e., that of ustethylin A in A. ustus 3.3904 (Zheng et al 2020), a rare human pathogen fungus (Pi et al 2015). In this pathway, the nonreducing PKS UttA is responsible for the formation of the key intermediate phenethyl benzoic acid. The final pathway product ustethylin A was detected as the predominantly accumulated metabolite (Fig. 1a)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
