WHITE COLLAR-1, A CENTRAL REGULATOR OF BLUE-LIGHT RESPONSES IN NEUROSPORA, IS A ZINC-FINGER PROTEIN

The Neurospora crassa blind mutant white collar-1 (wc-1) is pleiotropi cally defective in all blue light-induced phenomena, establishing a ro le for the wc-1 gene product in the signal transduction pathway. We re port the cloning of the wc-1 gene isolated by chromosome walking and m utant complementation. The elucidation of the wc-1 gene product provid es a key piece of the blue light signal transduction puzzle. The wc-1 gene encodes a 125 kDa protein whose encoded motifs include a single c lass four, zinc finger DNA binding domain and a glutamine-rich putativ e transcription activation domain. We demonstrate that the wc-1 zinc f inger domain, expressed in Escherichia coli, is able to bind specifica lly to the promoter of a blue light-regulated gene of Neurospora using an in vitro gel retardation assay. Furthermore, we show that wc-1 gen e expression is autoregulated and is transcriptionally induced by blue light irradiation.