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The VelB IDD promotes selective heterodimer formation of velvet proteins for fungal development

Summary

Fungi use special proteins called velvet factors to decide whether to make spores, form protective structures, or produce toxins. This research discovered that one velvet protein called VelB has a special flexible region that helps it choose the right partner protein to team up with. This teamwork determines what developmental path the fungus takes and what chemicals it produces, revealing a clever biological control system.

Background

Fungi possess velvet domain transcription factors that control development, virulence, and mycotoxin formation through homo- or heterodimerization. VelB is unique among velvet proteins in carrying an intrinsically disordered domain (IDD) within its DNA-binding velvet domain, a feature conserved across the fungal kingdom.

Objective

To characterize the molecular function of the VelB intrinsically disordered domain and determine its role in selective heterodimer formation with VeA or VosA, and its impact on fungal development and secondary metabolism.

Results

The VelB IDD destabilizes the full-length protein, promotes selective heterodimer formation with VosA but not VeA, prevents nuclear accumulation without partner interactions, and is required for efficient asexual spore formation. The IDD’s function in VosA interaction is conserved in Verticillium dahliae, and VeA presence counteracts VelB-VosA formation, suggesting VeA as the preferred interaction partner.

Conclusion

The VelB IDD represents a novel control mechanism for precise priming of fungal development through selective heterodimer formation and protein stability regulation, balancing VelB distribution between VelB-VeA and VelB-VosA complexes to appropriately coordinate mycotoxin production and sexual versus asexual development.
  • Published in:Life Science Alliance,
  • Study Type:Experimental Research,
  • Source: 10.26508/lsa.202503395, PMID: 41219003
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