Dissecting novel secondary metabolites pathways in Aspergillus homomorphus

M.E. Futyma1 , U. H. Mortensen1 , C. Hoeck2 , L. M. Petersen1 , Y. Guo1 , T. O. Larsen1 , C. H. Gotfredsen2 , J. B. Hoof1

Author address: 

1) DTU Bioengineering, Technical University of Denmark, Lyngby, DK; 2) DTU Chemistry, Technical University of Denmark, Lyngby, DK.

Abstract: 

Aspergillus homomorphus is a filamentous fungus belonging to section Nigri of Aspergillus genus. It is a genus known to produce harmful mycotoxins or industrially and pharmaceutically useful secondary metabolites, making it relevant to identify biosynthetic gene clusters (BGC) responsible for their biosynthesis. Recently, we discovered that A. homomorphus is particularly rich in interesting metabolites. Two examples are the family of homomorphosins (AF) and a yellow compound named CHO_015404. Here we present our efforts towards elucidation of the genetic requirements for these two biosynthetic pathways. As a first step we determined the putative BGCs of the discovered SMs by FungiSMASH analysis and predicted SM gene clusters available on JGI genome portal. In case of the homomorphosins, we based our search for a BGC on clusters containing a non-ribosomal peptide synthetase with two adenylation (AA) domains accompanied by two dimethylallyl tryptophan synthetases. For CHO_015404 our top BGC candidate contained type I Polyketide Synthase and Phenylalanine Amonnia Lyase. Performed bioinformatics analysis pointed into limited number of candidates that we chose to validate experimentally. With the advancing gene-editing toolbox for filamentous fungi developed in our group, we used CRISPR-Cas9 based deletion method expressing multiple protospacers targeting the gene of interest. At the current stage we have successfully identified the homomorphosins responsible BGC. We 76 assigned the enzymatic functions encoded by the gene cluster by generating deletion mutants and metabolites analysis by UHPLC-DAD-MS. The potential BGC of the yellow compound CHO_015404 is currently in the validation phase

2019

abstract No: 

300T

Full conference title: 

30th Fungal Genetics Conference 2019
    • Fungal Genetics Conference 30th (2019)