laeA

LaeA is a gene in filamentous fungi, most notably in Aspergillus species, that encodes a nuclear protein acting as a global regulator of secondary metabolism. It is a central component of the velvet regulatory complex, which also includes VeA and VelB, and links development with the production of secondary metabolites.

LaeA influences the expression of biosynthetic gene clusters responsible for secondary metabolites, such as sterigmatocystin and aflatoxins in Aspergillus nidulans and related species. In many strains, loss of laeA leads to reduced or abolished production of multiple metabolites, while changes in expression levels can alter the quantity or profile of metabolites produced. The protein is thought to act by modifying chromatin structure, including histone methylation marks, thereby modulating access to transcriptional machinery across biosynthetic gene clusters.

In addition to metabolic regulation, LaeA affects fungal development. Mutants lacking LaeA often show altered morphology, including defects in aerial hyphae formation and sporulation, which reflects the coordinated control of growth, development, and metabolism by the velvet complex.

LaeA is widely conserved among filamentous fungi and exerts significant influence on virulence in some pathogens, where the regulation of toxin production and other metabolites can affect pathogenicity. It was identified as a regulator of secondary metabolism and aerial development in Aspergillus nidulans and was later placed within the velvet complex that integrates environmental cues with developmental and metabolic outputs.

Discovery and context: LaeA was characterized in Aspergillus nidulans as a regulator of secondary metabolism and aerial hyphae formation. Its functional relationship with VeA and VelB helped define the velvet complex as a key regulator of fungal development and metabolite production.