Members of the Penicillium chrysogenum Velvet Complex Play Functionally Opposing Roles in the Regulation of Penicillin Biosynthesis and Conidiation

Abstract

A velvet multisubunit complex was recently detected in the filamentous fungus Penicillium chrysogenum, the major industrial producer of the ␤-lactam antibiotic penicillin. Core components of this complex are P. chrysogenum VelA (PcVelA) and PcLaeA, which regulate secondary metabolite production, hyphal morphology, conidiation, and pellet formation. Here we describe the characterization of PcVelB, PcVelC, and PcVosA as novel subunits of this velvet complex. Using yeast two-hybrid analysis and bimolecular fluorescence complementation (BiFC), we demonstrate that all velvet proteins are part of an interaction network. Functional analyses using single-and double-knockout strains clearly indicate that velvet subunits have opposing roles in the regulation of penicillin biosynthesis and light-dependent conidiation. PcVelC, together with PcVelA and PcLaeA, activates penicillin biosynthesis, while PcVelB represses this process. In contrast, PcVelB and PcVosA promote conidiation, while PcVelC has an inhibitory effect. Our genetic analyses further show that light-dependent spore formation depends not only on PcVelA but also on PcVelB and PcVosA. The results provided here contribute to our fundamental understanding of the function of velvet subunits as part of a regulatory network mediating signals responsible for morphology and secondary metabolism and will be instrumental in generating mutants with newly derived properties that are relevant to strain improvement programs.

Coordinated and Distinct Functions of Velvet Proteins in Fusarium verticillioides

“…Second, velvet proteins regulate sexual development and secondary metabolism. Deletion of veA orthologue completely impaired the formation of sexual fruiting bodies or resistant structures and the production of mycotoxins in A. nidulans, Aspergillus flavus, Aspergillus parasiticus, F. verticillioides, Fusarium fujikuroi, Penicillium chrysogenum, and Cochliobolus heterostrophus (24)(25)(26)(27)(28)(29)(30)(31). Similar functions of VelB were also found in F. oxysporum (21).…”

Fungal Morphogenesis, from the Polarized Growth of Hyphae to Complex Reproduction and Infection Structures

“…Velvet domain proteins form homodimers as well as heterodimers and recognize hundreds of genomic DNA-binding sites (360). Velvet domain proteins affect not only sexual and asexual development but also spore viability in different organisms (361)(362)(363)(364). A. nidulans veA was the first described velvet-domain-encoding gene (365), and its deletion results in the complete loss of sexual fruiting bodies (366).…”

Identification of growth stage molecular markers in Trichoderma sp. ‘atroviride type B’ and their potential application in monitoring fungal growth and development in soil

“…The molecular mechanism of chlamydospore formation is beginning to be elucidated; for example, in Trichoderma virens, the mutant vel1 induces a massive production of chlamydospores (Mukherjee & Kenerley, 2010). Orthologues of Velvet (vel1), a protein which belongs to a superfamily of fungal regulatory proteins, coordinate secondary metabolism, sexual and asexual differentiation and filament formation in fungi (Bayram & Braus, 2012;Choi & Goodwin, 2011;Dreyer et al, 2007;Hoff et al, 2010;Kopke et al, 2013;Ló pez-Berges et al, 2013;Merhej et al, 2012;Park et al, 2012;Sarikaya Bayram et al, 2010;Schumacher et al, 2013Schumacher et al, , 2015.…”