Acrophiarin (antibiotic S31794/F-1) from Penicillium arenicola shares biosynthetic features with both Aspergillus- and Leotiomycete-type echinocandins.

The antifungal echinocandin lipopeptide, acrophiarin, was circumscribed in a patent in 1979. We confirmed that the producing strain NRRL 8095 is Penicillium arenicola and other strains of P. arenicola produced acrophiarin and acrophiarin analogues. Genome sequencing of NRRL 8095 identified the acrophiarin gene cluster. Penicillium arenicola and echinocandin-producing Aspergillus species belong to the family Aspergillaceae of the Eurotiomycetes, but several features of acrophiarin and its gene cluster suggest a closer relationship with echinocandins from Leotiomycete fungi. These features include hydroxy-glutamine in the peptide core instead of a serine or threonine residue, the inclusion of a non-heme iron, α-ketoglutarate-dependent oxygenase for hydroxylation of the C3 of the glutamine, and a thioesterase. In addition, P. arenicola bears similarity to Leotiomycete echinocandin-producing species because it exhibits self-resistance to exogenous echinocandins. Phylogenetic analysis of the genes of the echinocandin biosynthetic family indicated that most of the predicted proteins of acrophiarin gene cluster exhibited higher similarity to the predicted proteins of the pneumocandin gene cluster of the Leotiomycete Glarea lozoyensis than to those of the echinocandin B gene cluster from A. pachycristatus. The fellutamide gene cluster and related gene clusters are recognized as relatives of the echinocandins. Inclusion of the acrophiarin gene cluster into a comprehensive phylogenetic analysis of echinocandin gene clusters indicated the divergent evolutionary lineages of echinocandin gene clusters are descendants from a common ancestral progenitor. The minimal 10-gene cluster may have undergone multiple gene acquisitions or losses and possibly horizontal gene transfer after the ancestral separation of the two lineages.