StuAp is a sequence-specific transcription factor that regulates developmental complexity in Aspergillus nidulans

Area of Science:

• Molecular and Cellular Biology
• Mycology
• Developmental Biology

Background:

• The Aspergillus nidulans Stunted protein (StuAp) is a transcription factor involved in regulating multicellular development during both asexual and sexual reproduction.
• StuAp belongs to a fungal transcription factor family with a conserved APSES domain, implicated in development and cell cycle control.

Purpose of the Study:

• To elucidate the function of the APSES domain within the StuAp protein.
• To identify the DNA-binding targets of StuAp and its role in gene regulation.
• To understand StuAp's contribution to the differentiation of specialized cells during fungal development.

Main Methods:

• Bioinformatic analysis to model the APSES domain structure.
• Identification of StuAp binding sites (response elements) in the A. nidulans genome.
• Functional assays in A. nidulans and budding yeast to determine StuAp's transcriptional activity (repressor vs. activator).

Main Results:

• The APSES domain is a sequence-specific DNA-binding domain with a basic helix-loop-helix (bHLH)-like structure.
• StuAp binds to specific DNA elements (A/TCGCGT/ANA/C) located upstream of developmental and cell cycle genes in A. nidulans.
• StuAp functions as a transcriptional repressor in A. nidulans but as a weak activator in budding yeast.

Conclusions:

• StuAp is crucial for regulating gene expression controlling both development and cell cycle progression in A. nidulans.
• The differentiation of sterigmata during conidiophore development is dependent on StuAp-mediated gene regulation.
• Fungal development processes, like sterigmata budding, may share regulatory mechanisms with pseudohyphal growth in budding yeast.