Activation of chsC transcription by AbaA during asexual development of Aspergillus nidulans.

The temporal and spatial regulation of chitin synthesis plays an important role in morphogenesis during fungal growth and development. Northern blot analysis showed that the transcription level of chsA, chsC, and chsD was significantly decreased in an Aspergillus nidulans abaA mutant. Electrophoretic mobility shift assays revealed that AbaA bound tightly to all three AREs (AbaA response elements) in the chsC promoter region. Experiments with the Saccharomyces cerevisiae heterologous expression system confirmed AbaA-dependent transcriptional activation of chsC. Taken together, these data suggest that AbaA plays an important role in chitin biosynthesis during conidiophore development by controlling the transcription level of certain chitin synthase genes.